The first Mongol expedition defeated Georgian armies in 1221–1222. George IV died fighting them in 1223 and his sister Rusudan made a desperate alliance against Mongols when she and her daughter Tamar married to Seljuk princes of Erzurum and Sultanate of Rum. The former enemies were now the closest allies (Battle of Köse Dağ) but that did not prevent the Mongol advance.