quest, a group of Teotihuacan natives were apparently residing near the Lost World complex. He also exerted control over other cities in the area, including Uaxactun, where he became king, but did not take the throne of Tikal for himself. Within a year, the son of Spearthrower Owl by the name of Yax Nuun Ayiin I (First Crocodile) had been installed as the tenth king of Tikal while he was still a boy, being enthroned on 13 September 379. He reigned for 47 years as king of Tikal, and remained a vassal of Siyah K'ak' for as long as the latter lived. It seems likely that Yax Nuun Ayiin I took a wife from the pre-existing, defeated, Tikal dynasty and thus legitimised the right to rule of his son, Siyaj Chan K'awiil II.
Río Azul, a small site 100 kilometres (62 mi) northeast of Tikal, was conquered by the latter during the reign of Yax Nuun Ayiin I. The site became an outpost of Tikal, shielding it from hostile cities further north, and also became a trade link to the Caribbean.
Although the new rulers of Tikal were foreign, their descendants were rapidly Mayanised. Tikal became the key ally and trading partner of Teotihuacan in the Maya lowlands. After being conquered by Teotihuacan, Tikal rapidly dominated the northern and eastern Peten. Uaxactun, together with smaller towns in the region, were absorbed into Tikal's kingdom. Other sites, such as Bejucal and Motul de San José near Lake Petén Itzá became vassals of their more powerful neighbour to the north. By the middle of the 5th century Tikal had a core territory of at least 25 kilometres (16 mi) in every direction.
Around the 5th century an impressive system of fortifications consisting of ditches and earthworks was built along the northern periphery of Tikal's hinterland, joining up with the natural defences provided by large areas of swampland lying to the east and west of the city. Additional fortifications were probably also built to the south. These defences protected Tikal's core
