Differing theories have been proposed regarding the Vijayanagara Empire’s origins. Historians agree the founders were supported and inspired by Vidyaranya, a saint at the Sringeri monastery to fight the Muslim invasion of South India. Writings by foreign travellers during the late medieval era combined with recent excavations in the Vijayanagara principality have uncovered much-needed information about the empire's history, fortifications, scientific developments and architectural innovations.
Before the early 14th-century rise of the Vijayanagara Empire, the Hindu states of the Deccan, the Yadava Empire of Devagiri, the Kakatiya Kingdom of Warangal, the Pandyan Empire of Madurai, and the tiny kingdom of Kampili had been repeatedly invaded by Muslims from the north, and by 1336 they had all been defeated by Alla-ud-din Khilji and Muhammad bin Tughluq, the Sultans of Delhi. The Hoysala Empire was the sole remaining Hindu state in the path of the Muslim invasion. After the death of Hoysala king Veera Ballala III during a battle against the Sultan of Madurai in 1343, the Hoysala Empire merged with the growing Vijayanagara Empire.
In the first two decades after the founding of the empire, Harihara I gained control over most of the area south of the Tungabhadra River and earned the title of Purvapaschima Samudradhishavara ("master of the eastern and western seas"). By 1374 Bukka Raya I, successor to Harihara I, had defeated the chiefdom of Arcot, the Reddys of Kondavidu, the Sultan of Madurai and gained control over Goa in the west and the Tungabhadra-Krishna River doab in the north. The original capital was in the principality of Anegondi on the northern banks of the Tungabhadra River in today's Karnataka. It was later moved to nearby Vijayanagara on the river's southern banks during the reign of Bukka Raya I. With the Vijayanagara Kingdom now imperial in stature, Harihara II, the second son of Bukka Raya I, further consolidated the kingdom beyond the Krishna River and brought the whole of South India under the Vijayanagara umbrella. The next ruler, Deva Raya I, emerged successful against the Gajapatis of Orissa and undertook important works of fortification and irrigation. Deva Raya II (called Gajabetekara) succeeded to the throne in 1424 and was possibly the most capable of the Sangama dynasty rulers. He quelled rebelling feudal lords as well as the Zamorin of Calicut and Quilon in the south. He invaded the island of Lanka and became overlord of the kings of Burma at Pegu and Tanasserim. The empire declined in the late 15th century until the serious attempts by commander Saluva Narasimha Deva Raya in 1485 and by general Tuluva Narasa Nayaka in 1491 to reconsolidate the empire.