1. Russian (Ермак) form of Turkic (irmak) "river"

2. Form of Ermolay

3. Form of Yaryema

Yermak Timofeyevich  (born between 1532 and 1542 – August 5 or 6, 1585), Cossack leader, Russian folk hero and explorer of Siberia. His exploration of Siberia marked the beginning of the expansion of Russia towards this region and its colonization.

In the mid 16th century the Tsardom of Russia conquered the Tatar khanates of Kazan and Astrakhan, thus annexing the entire Volga Region and making the way to the Ural Mountains open. The colonisation of the new easternmost lands of Russia and further onslaught eastward was led by the rich merchants Stroganovs. Tsar Ivan IV granted large estates near the Urals as well as tax privileges to Anikey Stroganov, who organized large scale migration to these lands. Stroganovs developed farming, hunting, saltworks, fishing, and ore mining on the Urals and established trade with Siberian tribes.

In 1558, the Stroganov merchant family received their first patent for colonizing "the abundant region along the Kama River", and in 1574 lands over the Ural Mountains along the rivers Tura and Tobol. They also received permission to build forts along the Ob and Irtysh rivers. Around 1577, the Stroganovs hired the Cossack leader Yermak to protect their lands from attacks of the Siberian Khan Kuchum.

In 1581 Yermak began his voyage into the depths of Siberia, that led to the conquest of the Khanate of Sibir. After a few victories over the khan's army, Yermak's people defeated Kuchum's main forces after a 3-day battle (October 23–25, 1582) on the banks of Irtysh. The remains of the khan's army retreated to the steppes. On October 26, Yermak captured the capital of the Siberia Khanate, Qashliq (17 km from the city of Tobolsk). Since Kuchum still had enough forces to resist, he suddenly attacked Yermak on August 6, 1585 in the dead of night and killed most of his people. Yermak was wounded and tried to swim across the Wagay River (Irtysh's tributary), but drowned under the weight of his own chain mail. The remains of Yermak's forces under the command of M. Mescheryak retreated from Qashliq.

Yermak's Cossacks had to withdraw from Siberia completely, but every year new bands of hunters and adventurers, supported by Moscow, poured into the country. Thanks to Yermak's having explored all the main river routes in West Siberia, Russians successfully reclaimed all Yermak's conquests just several years later.

Yermak's exploration of Siberia is reflected in the so-called Siberian Chronicles. His life and death have been subjects for numerous Russian songs, books, and paintings since the 16th century. In 1995 a historical biopic "Yermak" was shot.