Eastern Kazakhstan includes not only more of these uplands but also high mountains running west to east: the Altay in the northeast and the Tarbagatay in the east center. The Altay rise above 4500 meters at Mount Belukha on the Russian border. South of the Tarbagatay the land falls away into part of the Balkhash Basin--still 300 to 600 meters high-- and including--along the border with Almaty(1)--lakes Sasykkol' and Alakol'. Between the Tarbagatay and the Altay is Lake Zaysan(2), on the Irtysh(3) River.
That river flows from China northwest into the West Siberian Lowland, exiting Pavlodar northwest into Omsk Oblast and forming the center piece there until exiting into the Ural Federal District.
(1) Also spelled Almati.
(2) Also spelled Zajsan. It is one of Asia's largest lakes.
(3) Locally called the Ertys. Also spelled Irtys in transliterated Russian. The Ob'Irtysh river combination is Asia's second longest, fifth in the world.