Sayan are old and quite low (no more than 3000m) mountains, extending almost 1000 km along the Mongolian border, from Altai in the west to Baikal Lake in the east. The region is distinctly separated in two areas: Western and Eastern Sayan.
Western Sayan surrounds the basin of upper Yenisey River, one of major Siberian rivers and covers the territory of Tuva autonomous district (administrative center is the small town of Kyzyl). All the rivers there are either sources or tributaries of Yenisey: Ka-Khem, Biy-Khem, Kyzyl-Khem, Ulug-O, Khamsara, Khemchik, Alash, Abakan, and Ona. The landscapes are mainly flat steppe valleys surrounded by low and eroded mountains, therefore most rivers are easy class 2-3, with exception of maybe Ulug-O and Ona being class 3-4. Western Sayan has very poor road network and logistics is difficult here, so putting all these factors together very few whitewater kayakers want to travel to the area.
Rest of the description here is dedicated to Eastern Sayan, which has much more whitewater interests. Eastern Sayan typically implies north-eastern slopes of the mountain range separating Tuva from Central Siberian Plateau near the city of Irkutsk. We also include here Khamar-Daban Mountains located straight south to Baikal Lake because they're very similar to Eastern Sayan in all aspects.
The locals populating this area are Buryats, the only Buddhist people in Russia. They speak a dialect of Turkic but Russian is no problem here too. Just like in the Altai and Tuva, drunk addiction is a major issue in local settlements, thus it is recommended not to stay there for long to avoid unpredictable conflicts.
Type of Paddling
Self-supported multi-day runs of medium difficulty. Average gradient of most rivers is low by modern standards and there are many flat sections on all rivers. Having said this, there are very nice gorges and sometimes even extreme sections on these rivers. Most rivers will involve long way to the put-in (trekking is often required) and long flat paddling to the take-out at the end. Therefore it would be difficult to run large number of rivers during one single trip and rented car is not too useful as it will stay idle most of the time. Almost no river has road alongside and emergency escape is difficult.
Season & Climate
July-August. Climate is much worse comparing to the Altai. It is typically colder and weather is very unstable with unpredictable heavy long rains all the summer. Rivers are mainly at moderate altitude of 500-1200 m and are rain-fed so water level depends on weather significantly. After some heavy rains up the valley it's likely to get sudden and huge floods in lower gorges where river raises 5-10 m within few hours and becomes unrunnable. Mosquitoes are - as almost everywhere in Siberia - wicked, hungry and countless, so appropriate precautions are necessary. Besides that, Sayan is a tick-prone area and proper vaccination against encephalitis is recommended.
Getting There & Away
The only reasonable way to get there is a flight to Irkutsk - the biggest city of Baikal region, having numerous flight connections to most of Russia. Train journey there is about 4 days (one-way) from Moscow and is not an option unless your time is unlimited.
Local access to most rivers is done by car via small town of Sludyanka on the west edge of Baikal. From here there's a road going west via Kyren, Mondy and Orlik to the hearth of Sayan Mountains. The road has some local forks passable for good 4x4 vehicle. Still, many rivers will require more or less trekking to get to the put-in.
Local access to river in Khamar-Daban range (south shore of Baikal Lake) also starts from Sludyanka, but then you should reckon on your feet only - there's no road in that direction.
There is an option to hire helicopter directly in Irkutsk which may be a wise alternative to a multiday car ride and trekking, especially for some remote rivers.
There's no paperwork required in East Sayan, despite proximity of the Mongolian border. Eastern part of Khamar-Daban is a strictly closed nature reserve prohibited to enter for anyone so you don't need (i.e. you can't get) any permit too.