Southward from the Siberian Line the obvious next step was a line of forts along the Syr Darya eastward from the Aral Sea. This brought Russia into conflict with the Khan of Kokand. In the early 19th century Kokand began expanding northwest from the Ferghana Valley. About 1814 they took Hazrat-i-Turkestan on the Syr Darya and around 1817 they built Ak-Mechet ('White Mosque') further downriver, as well as smaller forts on both sides of Ak-Mechet. The area was ruled by the Beg of Ak Mechet who taxed the local Kazakhs who wintered along the river and had recently driven the Karakalpaks southward. In peacetime Ak-Mechet had a garrison of 50 and Julek 40. The Khan of Khiva had a weak fort on the lower part of the river.