Siege of Pavia, the kingdom came under the Frankish domination of Charlemagne. The Iron Crown of Lombardy (Corona Ferrea) was used for the coronation of the Lombard kings, and the kings of Italy thereafter, for centuries. The primary sources for the Lombard kings before the Frankish conquest are the anonymous 7th-century Origo Gentis Langobardorum and the 8th-century Historia Langobardorum of Paul the Deacon. The earliest kings (the pre-Lethings) listed in the Origo are almost certainly legendary. They purportedly reigned during the Migration Period; the first ruler attested independently of Lombard tradition is Tato. The actual control of the sovereigns of both the major areas that constitute the kingdom – Langobardia Major in the centre-north (in turn divided into a western, or Neustria, and one eastern, or Austria and Tuskia) and Langobardia Minor in the centre-south, was not constant during the two centuries of life of the kingdom. An initial phase of strong autonomy of the many constituent duchies developed over time with growing regal authority, even if the dukes' desires for autonomy were never fully achieved. The Lombard kingdom proved to be more stable than its Ostrogothic predecessor, but in 774, on the pretext of defending the Papacy, it was conquered by the Franks under Charlemagne. They kept the Italo-Lombard realm separate from their own, but the kingdom shared in all the partitions, divisions, civil wars, and succession crises of the Carolingian Empire of which it became a part until, by the end of the ninth century, the Italian kingdom was an independent, but highly decentralised, state. Constituent of the Carolingian Empire The death of the Emperor Lothair I in 855 led to his realm of Middle Francia being split among his three sons. The eldest, Louis II, inherited the Carolingian lands in Italy, which were now for the first time (save the brief rule of Charlemagne's son Pepin in the first decade of the century), ruled as a distinct unit. The kingdom included all of Italy as far south as Rome and Spoleto, but the rest of Italy to the south was under the rule of the Lombard Principality of Benevento or of the Byzantine Empire. Following Louis II's death without heirs, there were several decades of confusion. The Imperial crown was initially disputed among the Carolingian rulers of West Francia (France) and East Francia (Germany), with first the western king (Charles the Bald) and then the eastern (Charles