Warring States Period

Several decades in the past before the Ninja Village System was set up by Hashirama Senju, there was an extremely bloody period in history where the hundreds of individual shinobi clans fought in constant, bitter warfare. During this time period, the average life-span was a scant 30 years for both shinobi and civilians alike. However, the biggest loss in the era was the thousands of conscripted children in the individual clans which were forced to fight in the front lines, often being killed by the more experienced adults which lowered the overall life expectancy. Hashirama lost his brothers Itama Senju and Kawarama Senju in this era, while Madara Uchiha lost four brothers with Izuna being the only survivor of them.

Hashirama, Tobirama, Madara, and Izuna grew up, fighting in this era and gaining fame and power during it. While they had met out of the conflict and became friends, Hashirama and Madara became enemies for most of this time, fighting several battles which had little to no conclusion. Also during this time, Madara and Izuna discovered the secret of the Sharingan; becoming the first two Uchiha to awaken the Mangekyō Sharingan after killing their comrades. During these constant battles with the Senju Clan, Madara's vision degraded further and further until he had to steal his brother's eyes, gaining a Eternal Mangekyō Sharingan to keep fighting his former friend and rival during the War.

However, after decades of fighting, most of the clans in the Land of Fire, under the Uchiha and Senju banners formed a first lasting truce after being bled dry. The only person who opposed the peace was Madara, who argued for the Uchiha Clan to continue the fighting but was persuaded to join in a permanent alliance with the Senju Clan, and Konoha was formed.