This basin used to be known as the Headwaters Basin (Shwaildor) and you may still hear that term used, but it has fallen out of use since the city of Yclel-vi grew large.
This is another equatorial highland. There is pronounced compression folding in the area causing many small ridges running north and south, similar to that found in the Vesh Basin. The whole basin is actually a great compression fold in the crust.
In this basin are some of the largest areas of shield rocks in an accessible area. These are mantle rocks that have become exposed as the former equatorial bulge has eroded away. They are hard and poor in nutrients so they are largely barren.
There are two major levels to the basin. The northern sections are about a mile above sea level, barometrically. The city is near sea level, the southern part of the basin up to one mile below. The city is at the top of a steep escarpment and the water power is used in industry. The upper basin gets frost every week, and in the highest points it can be severe. The city gets frost every week but is no more severe than the Yakahn. The southern part of the basin is largely frost free, but it occurs often enough that settlement was not possible in ancient times.
There is some disagreement among geographers about the boundaries of this basin. In the past the boundary between the Norbin and Shwaildor basins was at Harmoose Carry. Geologically the basin extends nearly to Tarsitar, and in recent times the cultural boundary has moved in that direction. Geologically the Kugenzglaw Valley is also part of this basin. In the past it has been considered part of the Highlands, but with the growth of the city and the opening of a full sized canal thru the Ascetic Pass, more people of the valley consider themselves part of the Yclel-vi Basin.
Geologically the basin extends far deeper into the Lumpral Basin than makes sense culturally, down into the regions to the west of the Dystian, Naiderdon and Imbrey Plateaus, far beyond this map.
Until the Energy Age most of this area was uninhabitable because of the weekly freeze. After the hardy onion was developed a few Nordic tribes settled in the upper basin, Enurate tribes in the lower. They left no written history, had no large settlements and were unknown to the outside world. Explorers from the Salvador Basin did not push thru the Ascetic Pass and the Fmak never came this far east across the desert. Thus there isn't much history in this basin.
The region was explored by the Highlands Elves around the time of classical Greece, but no large settlements were erected. This area was just a stop over on the way to the lush Norbin Basin. Large scale settlement didn't begin until nearly a thousand years later, making this one of the newest basins on the planet. Before the Instinct, Enurate tribes from the Lumpral Basin made settlement of the lower part of the basin difficult. Since the Instinct, people have been able to enter the area without violent conflict.
In modern times the basin has grown in population relatively rapidly. Abundant water power makes it prosperous, but the cold of dark requires fuel for heating. There are abundant shaftwood forests in the area to supply those needs. The dense city requires less heating than a more spread out settlement would, and the shaftwoods used for housing have good insulating properties.
The upper basin could almost be considered part of the Highlands. The population has a little more Nordic and Enurate in it than the Highlands, but you'll be there a few days before you notice it. There is actually a higher percentage of Highland Elves in Yclel-vi than in Kugenzglaw.
There is a little less emphasis on being pretty than in the Highlands, but it is still an important part of life. The city has its own music, art and literature, but the styles are very similar to the Highlands and to Norbin. Outdoor recreation is slightly more popular than in the Highlands. There are less diddle cooks and the bioluminescent lighting is not used. The small powered launches called 'needleboats' are common in the city, but most of them are public, there are not as many private ones as in the Yakhan.
The distribution of income is more equitable in this basin than either the Highlands or Norbin, nearly as even as Dos. Yclel-vi city is a large manufacturing center with many small enterprises. The electronics industry is strong here, and video screens are more common than in the Highlands, but not as common as in Bordzvek. The media is important, and there is more video news in this basin than any other. This video is what is uniting the distant parts of the basin into a common culture.
The lower basin has a larger percentage of Enurates and more influence from Enurate culture. Even today some will consider the city of Ingz Myop to be in the Lumpral Basin because it is so much like many other Enurate cities along the Lunstran. There are many churches, few crystal buildings, restaurants bring meals to a table instead of letting customers order from a menu. There are few spray toilets and little data access. A dialect of Dulette is common, but most people are also fluent in Kassidorian.
The city of Yahntiva however is very much a city of Highland Elves with crystal buildings, an efficient waterfront, archwood buildings and lots of entertainment opportunities. That city is as modern as any in the Highlands. Most use Kassidorian as their everyday language, most know nothing else. Incidently, almost no one in this basin has ever heard of a language called Centish.
The countryside of the lower basin is a mixture of Highland Elf and Enurate culture. The cultures stay relatively separate, even though members are in close proximity. In some areas there is still some tension, especially regarding religious issues. The Elves tend to stay more along the waterways and in the towns, the Enurates tend to stay in more remote areas and in smaller settlements. There are some people and neighborhoods that try to borrow from both cultures.
The Highlands Elves dress as they do in the Highlands with long tees in the warm part of the week and nightcoats for the dark. The dye jobs on the tees are usually not as flamboyant and more geometrical. Because scamps are abundant, the nighcoats are often all fur.
The Enurates still dress somewhat more conservatively than the Elves, but not as traditional as in the Lumpral Basin. Many of them have adapted Elvish dress because the factories in the cities make it quite a bit cheaper than their traditional dress.
Meeting a companion in the lower basin is a little more difficult than in the Highlands. The Enurates do not have sex clubs as a first order approximation, but many of them do frequent the Elvish establishments. Enurate women do tend to be more buxom than the Elves, but they are less likely to be looking for a casual affair. If you spend much time with one you may be in for a scene when you leave.
The city of Yclel-vi is what made this into a basin of it's own. It is one of the newest big cities on the planet. It was created in the years around 1350ad. by a canal over a hundred miles long that diverted the Lunstran to a site much more suitable for water power on the Yclel River. In 1500ad. there were less than two million residents in the current urban area, but most of the present central city was under water. By 2000ad. there were nearly thirty million and the lake had been filled where downtown stands today. Today, 4100ad., there are forty five million and only a small pool of the lake remains.
The city is laid out in one of the few flat areas on the top of the escarpment. When the dam was first built where the Lunstran picks up the Yclel, there was a lake covering dozens of square miles. Today that has been filled in by the city, but gives the central city a grid of canals. Canals extend up the valley of the Yclel for dozens of miles. Most of the city can be reached without going thru a lock.
Because of the canals, the city is sometimes described as a cross between Trenst and the Yakhan, but it is neither. The buildings of the center city stand in the water of the lake, but the main channel is laid out as if the Lunstran takes a loop around the center of the city before reaching a small lake at the top of the lockway. Small canals network the center city and fan out across the former lake bed to all parts of the city. The commercial waterfront is on the main channel, the main beach is the dam of that small lake, one must cross the locks on a wide and lofty pedestrian bridge to get there.
The main streets are about six floors above the water. The lower floors are industrial, the main streets are in the commercial level above that. There is another level of streets at the upper end of the commercial levels. Up to that level the city is mainly built of crystal and stone. The style is rather geometric but not overly harsh. Most entertainment venues are in the upper levels of the commercial space. Most shopping in the lower level of streets, with business offices in between.
Above the entertainment street level, the buildings change to grown. They are mostly great shaftwoods, false mesawoods and clumped multibreak hangleaves. In these are the residential levels, and there are about twenty floors of them thruout the central city and along the main waterfronts on the far side of the channel. There are slender bridges between these apartment trees at various levels. There are hundreds of elevators in the city, using almost as much of the available water power as the city's industry does.
The city is probably the most brightly lit for Nightday of any city on the planet with the possible exception of Bordzvek. There is an extensive system of plumbed gas lanterns using methane generated from sewage and other waste. In addition there are large globes of softly glowing phosphors that line the canals. These devices store energy chemically from the light part of the week and release it when turned on during Nightday. This technology is used extensively in Bordzvek, but mainly indoors.
This is the second densest city after Zhlindu. Like Zhlindu there is a very lively entertainment scene. The music is more like the Highlands than Zhlindu, though the Zhlindu sound is popular here. The cinema seems to concentrate on psychological mysteries or sexual comedies. Technically it is beyond what's legal in the Empire. Video news is an important industry here. Nearly all of it seen in the basin is produced in this city. Local news is usually disseminated by local yearly magazines. The news is more economic and cultural than anything we see on Centorin. There is some crime to report, but no politics or warfare.
This basin is well worth visiting if you have the time. The tubes now reach as far as Kugenzglaw, but it is still a journey of two local years from there. The trip is comfortable and interesting. You will go on a sailing packet that will be animal-drawn at times. On most of them you will stop at river towns for meals but you will normally sleep on the boat. It is customary to share a cabin with someone of the opposite sex, and there are gathering places to chose a cabin mate. The Kugenzglaw and Yclel valleys are identical, open woodland and distant mountains, big (for Kassidor) farms and ranches. For that matter the upper Lunstran and upper Kshoned Valleys are also more of the same, should you head on to Norbin. The skiing is surreal but there is no way up but to climb. The Ascetic Pass is no longer the problem it was in ancient times and even in the dead of winter when the canal freezes, there are plenty of places to winter over until the canals thaw. They are never frozen more than four local weeks.
Dark will be cold at all times of the year, more so in the upper basin than the lower. The climate in the lower basin is not as severe as Kex, but the long darks can get winter temperatures into the 20'sF (negative single digits C) in the upper basin. Steep little mountains are everywhere, either covered with shaftwoods, terraced for farms or steep pastures for scamps above the tree line.
The basin has less big game than basins like Zhlindu, nZhiktar, Trenst or Yondure, but the small game enthusiast will find better hunting here than almost anywhere in the Highlands. The top predator here is the bandazak, a 900 pound theiropsoid with very long legs and snout. They are smart enough to respect a crossbow and will not come near if they see it. Even so, it is best not to go out alone. There are many hunting safaris you can join and in the evenings they do party. There are usually enough women along and the guides have recipes using wild herbs and spices that are outstanding.
In the upper basin, meeting people is the same as in the Highlands. There are no chains of clubs to let you know what the atmosphere is, but there are signs posted as in the Highlands indicating what is permissible. If she invites you home you do not need to fear, she will have a home at least as comfortable as a commoner on Centorin. You are less likely to run into something kinky than you are in the Highlands, and you are less likely to run into dangerous drugs.
Right outside the center of Yclel-vi city is one of the wonders of the planet, Sculptured Canyon Park. There is a small stream that makes it's way down into the former lake that has carved a spectacular canyon into the rock. There are three sections to the canyon. In the lower section, slow water winds thru a sensuously carved canyon for over a mile. The rock has brightly colored layers but is of uniform hardness so the layers show as color only. The erosion is very smooth, but the carvings make lots of shapes. Pinnacle islands stand in the channel. The banks are lined with homes for the first half mile, then the land belongs to the park.
The center of the park is a series of natural waterslides. The rock is smooth enough and a cover of gelatinous algae is maintained that makes it very slippery. There is a skein of channels, ranging from .93 miles to 1.67 miles. They vary in difficulty and are plainly marked. The channel on which people have been killed is the most clearly marked of all. Most of the people in the park are making their way back up to the top for another ride. There are multiple bucket lifts, wagon rides and a cable car, all charging various prices. There are multiple hiking paths, and there are plenty of refreshments on the way. Nudity is universal, and this is the top body watching spot in the city. Besides that, the safe routes thru the slide are a lot of fun. For a local the three penny admission to a ride is steep, and half the people in the park just hang out at the bars and never do take a slide. There are bands on Afternoonday and the place is a crush.
The third section of the canyon is above the waterslides. The sculpted canyon continues another mile up three different streams and can be hiked and waded. There are only a few more taps and cooks up here and it is much more quiet than the central part of the park. The main activity here is enjoying the beauty of the carvings. They are smaller in scale here. Some resemble human figures, some resemble the trunks of trees. One even looks like a surreal deer with four legs standing on a pedestal with it's nose gazing up at the sky. The other activity in this part of the park is finding a little privacy in one of the swirls of the side canyons.
Also right outside the central city is one of the better zoological gardens on the planet. They have only land animals, but there is a large area open to the public where one can actually see a good representation of the variety of Kassidor's wildlife. There is even a section where one can play with some of the animals. There are no dangerous animals in that section, but this park has the only caged theirops known to be alive. Most scientists agree it must have been lobotomized to tolerate captivity. But this is about the only place in the universe you can get to see a live theirops and live to tell about it. The park does not have a kranjan or obront or any of the greater blademouths. The budget cannot afford to feed one.
As in Dos, perhaps the greatest danger you face in visiting here is that you may never want to return. Making a good living here might be a little difficult at first, but if you meet someone with a nice home that you feel comfortable with, the temptation can be very great. This is probably the second most likely basin for a Centorin to feel comfortable in, but it is so much easier to reach than Bordzvek that many more Centorins have settled here. The latest estimate is that nearly ten thousand have reached here and never returned. Data service is good enough that one can keep in touch with the home world on a fairly regular basis.