At the time of Temür's death (1405) the nomadic population of the Dasht-i Qipchāq was in a state of turmoil. After the defeat of Toqtamïsh Khan and the devastation caused to the Ulus of Jochi by the campaigns of Temür, this ulus began to disintegrate. The eastern part of it, the Kök Orda (or the former Ulus of Orda), broke up into several independent groups, the most powerful of which was the tribal confederation of the Manghïts. This confederation, which became known west of the Volga under the name of the Noghay and was ruled until 1419 by the famous amir (or beglerbegi) Edigü, in the first quarter of the fifteenth century occupied the territory between the Volga and the Yayïq. East of the Manghïts, the nomadic population of the Ulus of Shiban became known under the collective name Uzbek (actually, Özbek) apparently already in the second half of the fourteenth century. It is usually assumed (following the explanation given by the seventeenth-century khan-historian Abu'l-Ghāzī of Khiva) that this name was given due to the conversion to Islam of the entire Ulus of Jochi carried out by Uzbek Khan in the first quarter of the fourteenth century. In the early fifteenth century the authority over the Uzbeks was contested by several descendants of Shiban. One of them, Jumaduq, son of Ṣüfī Oghlan, was proclaimed khan in 1425/6, but his authority seems to have been limited to the southern regions of the Ulus of Shiban.