Madara Uchiha was a legendary shinobi who led the Uchiha clan prior to, and after the formation of Konohagakure. After allying with his rival, Hashirama Senju and the Senju clan, he and his clan helped in the founding of Konoha.
Before the era of ninja villages, Madara and his younger brother, Izuna, were considered the most gifted members of the Uchiha clan. Even by his clan's standards, Madara's chakra was especially strong. He grew up constantly competing and training with Izuna and in their efforts to surpass each other, each awakened their Mangekyō Sharingan. With the power of the Mangekyō, the two brothers took control of the clan, with Madara becoming its leader. Under his leadership, the clan conquered all they came across. Because of the never-ending series of battles at the time, Madara eventually began to suffer from overuse of the Mangekyō Sharingan, leaving him blind. In order to regain his sight he took Izuna's eyes for himself, granting him an "eternal" Mangekyō Sharingan with which he led the Uchiha clan to prosperity. While Itachi claimed that Madara took Izuna's eyes without his consent, Tobi, while retelling this event to Sasuke, stated that Izuna willingly gave up his eyes to Madara for the good of his brother and clan. It is unknown which is true.