One of the main reasons Stefan honored vassal obligations under Bayezid was his sister Olivera that had been in the Sultan's harem. Olivera which was just one of the women in the harem of Bayezid, was at the same time a kind of hostage. Stephen loved his sister, and Bayezid knew this as his weakness. In fact, Stefan's attacks on the Tatars which surrounded the Sultan were desperate attempts to rescue his sister, but with no success. She was later released, through an agreement that was signed between Stefan and Timur. It seems that a ransom wasn't paid, thanks to the great respect that Timur had for Olivera's brother Stefan, and she returned to Serbia (Spring 1403), and a little later she settled permanently in Stefan's castle, in Belgrade. It is interesting that a group of imprisoned Serbs were taken to magnificent Samarkand where they are employed on construction works. On the other hand, Timur's forces had already left Asia Minor in 1403, and Timur himself died in early 1405, during his expedition to China. In the Ottoman Empire, Bayezid's capture, and then his death, brought on a civil war between his sons for throne.