The third insurrection occurred in 1735, at the time of the foundation of Orenburg, and it lasted for six years. From at least the time of Peter the Great there had been talk of pushing southeast toward Persia and India. Ivan Kirillov drew up a plan to build a fort to be called Orenburg at Orsk at the confluence of the Or River and the Ural River southeast of the Urals where the Bashkir, Kalmyk and Kazakh lands join. Work was started at Orsk in 1735, but by 1743 'Orenburg' was moved about 250 km west to its present location. The next planned step was to build a fort on the Aral Sea. This would involve crossing the Bashkir country and then the lands of the Kazakh Lesser Horde, some of whom had recently offered a nominal submission.
Kirillov's plan was approved on May 1, 1734 and he was placed in command. He was warned that this would provoke a Bashkir rebellion, but the warnings were ignored. He left Ufa with 2,500 men in 1735 and fighting started on the first of July. The war consisted of many small raids and complex troop movements, so it cannot be easily summarized. For example: In the spring of 1736 Kirillov burned 200 villages, killed 700 in battle and executed 158. An expedition of 773 men left Orenburg in November and lost 500 from cold and hunger. During, at Seiantusa the Bashkir planned to massacre sleeping Russian. The ambush failed. One thousand villagers, including women and children, were put to the sword and another 500 driven into a storehouse and burned to death. Raiding parties then went out and burned about 50 villages and killed another 2,000. Eight thousand Bashkirs attacked a Russian camp and killed 158, losing 40 killed and three prisoners who were promptly hanged. Rebellious Bashkirs raided loyal Bashkirs. Leaders who submitted were sometimes fined one horse per household and sometimes hanged.
Bashkirs fought on both sides (40% of 'Russian' troops in 1740). Numerous leaders rose and fell. The oddest was Karasakal or Blackbeard who pretended to have 82,000 men on the Aral Sea and had his followers proclaim him 'Khan of Bashkiria'. His nose had been partly cut off and he had only one ear. Such mutilations are standard Imperial punishments. The Kazakhs of the Little Horde intervened on the Russian side, then switched to the Bashkirs and then withdrew. Kirillov died of disease during the war and there were several changes of commander. All this was at the time of Empress Anna of Russia and the Russo-Turkish War (1735–1739).