Grandson of Genghis Khan who commanded the Mongol western campaign of 1236–1242, crushed Hungary at Mohi, and founded the Golden Horde that dominated the Rus' lands for over two centuries.
Batu Khan led the largest sustained westward assault the Mongol Empire ever mounted. As son of Jochi and grandson of Genghis Khan, he was given the westernmost inheritance of the empire, and between 1236 and 1242 — with the veteran general Subutai directing strategy — his armies destroyed Volga Bulgaria, burned the cities of the Rus' from Ryazan to Kiev, and broke the field armies of Poland and Hungary within days of each other in April 1241.
The Battle of Mohi left Hungary open to a year of devastation; only the news of the great khan Ögedei's death turned the armies east in 1242. Batu never returned to Europe. Instead he built a state: from Sarai on the lower Volga he ruled the Jochid ulus — the Golden Horde — as khan and imperial kingmaker, holding the Rus' princes as tributaries and deciding the imperial succession itself when he raised Möngke to the throne in 1251.
Batu was born around 1205, a son of Jochi, the eldest and most contested of Genghis Khan's sons — the whispers about Jochi's paternity, born after his mother Börte's captivity, shadowed the whole line. The sources name no birthplace and no reliable birth year; like most of the early Chinggisid princes he is visible only where the Persian historians Juvaini and Rashid al-Din, the Rus' chronicles, or the Secret History happen to light him up. When Jochi died shortly before Genghis in 1227, Batu received the paternal inheritance: the lands "as far west as Mongol hooves had trodden" — a grant that was less a territory than an instruction to conquer one.
The tradition that reached the Persian historians remembered Batu as "Sain Khan" — the Good or Wise Khan — a byname that reflected his reputation for generosity and rough justice within the Horde rather than any gentleness toward enemies; the Rus' chronicles, written by the conquered, record the same man as the destroyer of Ryazan, Vladimir, and Kiev. Both portraits are source-bound and both are true to their vantage: to his own people a steady, open-handed lord; to the lands he broke, a catastrophe.
What the records agree on is political weight rather than battlefield brilliance. The friar William of Rubruck, who saw him in the 1250s, noted his commanding presence and compared his state to a court of kings; Juvaini stresses the deference even reigning khans paid him. His feuds were dynastic and he pursued them with patience — the drunken quarrel at the victory feast on the western campaign, when his cousins Güyük and Büri insulted him, became a decade-long enmity that Batu settled not with armies but by outliving Güyük and installing Möngke as great khan in 1251. Strategy on campaign he was content to leave to Subutai; power he kept for himself.
The great western campaign decreed by the khan Ögedei began in 1236: a coalition of Chinggisid princes nominally under Batu, with Subutai as its operational brain. Volga Bulgaria was destroyed first; then, in the winters of 1237–38 and 1239–40 — the Mongols deliberately campaigned when the rivers froze — the cities of the Rus' fell one after another: Ryazan, Vladimir, Torzhok, and in December 1240 Kiev itself, stormed and sacked so thoroughly that travellers years later reported fields of bones. The Rus' principalities passed under a tributary yoke that would last more than two centuries.
In 1241 the army split to strike Latin Europe. A northern wing shattered the Polish-Silesian host at Legnica on 9 April; two days later Batu and Subutai destroyed King Béla IV of Hungary's army at the Battle of Mohi on the Sajó river, forcing the bridge in a night operation while Subutai's wing crossed downstream to envelop the Hungarian camp. Hungary was ravaged for a year and Béla hunted to the Adriatic. Then, in the spring of 1242, word came that Ögedei had died in Mongolia in December 1241, and the whole army withdrew through the Balkans to the steppe. Whether the succession alone caused the withdrawal is still argued — pasture, losses, and the campaign's design all get weight in modern accounts — but Europe was never invaded on that scale again.
From 1242 until his death Batu ruled his father's ulus from the lower Volga, where the city of Sarai grew up as his capital — the seat of what later centuries called the Golden Horde. The Rus' princes travelled there to receive their patents to rule: Yaroslav of Vladimir came, and so, famously, did Alexander Nevsky, whom Batu's court confirmed and used. Tribute, census, and the yarlik system of investiture — the machinery of two hundred years of Mongol overlordship over the Rus' lands — took shape under him.
Within the empire he was the kingmaker. He refused for years to attend the election of his enemy Güyük, and the two were near open war when Güyük died in 1248. Batu then threw the weight of the Jochid ulus behind Möngke, son of Tolui, and the assembly of 1251 that crowned him — and the purge of the Ögedeid princes that followed — made Batu effectively co-ruler of the empire, supreme in its western half. The aqa, the senior prince of the Chinggisids: that, more than any battle, is what Batu had become by his last years.
Batu died on the lower Volga around 1255 — the Persian and Rus' sources scatter the date between 1255 and 1256, and record no dramatic circumstance; he seems simply to have died in his own horde, in his fifties. His burial place is unknown, as is usual for the Chinggisids, whose graves were concealed. The great khan Möngke confirmed Batu's son Sartaq — reported by Rubruck to be sympathetic to Christianity — as his successor, but Sartaq died within a year or two, and after the brief reign of the boy Ulaghchi the Horde passed to Batu's brother Berke, under whom it turned toward Islam.