Geography of Uzbekistan in Uzbekistan is best exemplified by the catastrophe of the Aral Sea. Because of diversion of the Amu Darya and Syr Darya for cotton cultivation and other purposes, what once was the world's fourth largest inland sea has shrunk in the past thirty years to only about one-third of its 1960 volume and less than half its 1960 geographical size. The desiccation and salinization of the lake have caused extensive storms of salt and dust from the sea's dried bottom, wreaking havoc on the region's agriculture and ecosystems and on the population's health. Desertification has led to the large-scale loss
Kazakhstan–Uzbekistan border sparsely populated and traverse largely desert areas, in stark contrast to the western third which is densely populated, containing some of the largest towns in Uzbekistan and southern Kazakhstan. The eastern-most section is mountainous and contains a series of national parks (Sayram-Ugam National Park and Aksu-Zhabagly Nature Reserve in Kazakhstan and Ugam-Chatkal National Park in Uzbekistan. Uzbekistan’s Jizzakh to Sirdaryo railway crosses through Kazakhstan briefly, a legacy of the Soviet era where infrastructure was built without regard to what were then internal boundaries. Russia had conquered Central Asia in the 19th century by annexing the formerly independent Khanates of Kokand