Transactions between ancient communities across the varied ecological zones of Central Asia produced a complex commercial structure. Pastoral nomads on the steppe and farmers in the oases traded to supplement their livelihoods. Domestication of horses on the Eurasian steppe around four thousand years ago was a driving force stimulating interactions between the horse riders and settled farmers. Conflicts between horse-riding nomadic powers on the steppe and Chinese empires initiated the silk-horse treaty trade, which lasted until the end of the Tang Dynasty. Domestication of camels around 3000 bce enabled transportation across deserts and thus linked the oases to one another and to the outside world. Especially after the invention of a new saddle for the Bactrian (two-humped) camel, the caravan trade flourished as the major means of commercial interchange in the Central Asian deserts during the 1st millennium ce. Sogdian city states around the Syr and Amu Rivers prospered through farming, and the Sogdians became the agents of trade among Chinese empires, Persian empires, South Asian states, and various Turkic empires on the steppe. After the Islamic conquest of Central Asia, the Sogdians gradually submitted to Islamic rule, transforming themselves into Muslim traders and continuing to play an essential role in linking Central Asia to the wider Eurasian commercial world. Means of transportation and means of communication provided the infrastructure for trade. Governments and major trading communities such as the Sogdians were active in building trading networks, and religious movements such as the spread of Buddhism facilitated the formation of commercial networks.
