Magyars

This entry is a people/tribal confederation, not a single state

The Magyars (Hungarians) were a Finno-Ugric–speaking people (with strong Turkic cultural admixture) who formed a tribal alliance in the Pontic steppe. They lived under a dual kingship reminiscent of the Khazars, with a sacral ruler (the kende) and a de facto military leader (the gyula) — Britannica notes the kende had "minimal powers" while the gyula was the de facto leader. The confederation was traditionally described as the "On-Ogur" ("Ten Tribes"), from which, via Slavic mediation, the name "Hungarian" derives.

Pressed by the Pechenegs (and following a joint Pecheneg–Bulgarian attack in 894–895), the Magyars under Árpád (grand prince c. 895–907) and the co-ruler/kende Kurszán crossed the Carpathians in the Honfoglalás ("land-taking"), the conquest of the Carpathian Basin. This is conventionally dated to 895–896; Wikipedia notes the older date of 896 has "proved to be erroneous," and the settlement was a planned process spanning roughly 862–895. They overran the remnants of Great Moravia.

From their new base the Magyars launched decades of devastating raids across Europe (researchers count some 47 campaigns between 899 and 970). They won the Battle of Pressburg (Brezalauspurc, 4 July 907), securing the basin against the Bavarians, and the Battle of Brenta (899). Their raids were finally halted by the crushing defeat at the Battle of Lechfeld (955) near Augsburg, where the German king Otto I destroyed a major Magyar army. Lechfeld ended the western raids and accelerated the Magyars' transition to a settled, Christian kingdom, culminating in the coronation of Stephen I as first King of Hungary in 1000/1001.