The Jasz people came to the Kingdom of Hungary, together with the Cumanians ( people) when their lands to the east, in some in the later Moldavia (see Iași and Jaszvasar) were invaded by the Mongol Empire in the mid-13th century. They were admitted by the Hungarian king, Béla IV Árpád, who hoped that the Jaszs would assist in resisting the Mongol-Tatar invasion. Shortly after their entry, the relationship worsened dramatically between the Hungarian nobility and the Cumanian-Jasz tribes, which then abandoned the country. After the end of the Mongol-Tatar invasion they returned and settled in the central part of the Pannonian Plain, near the rivers Zagyva and Tarna.