Boroldai

Serving under Jochi's successor and son, Batu Khan, Borolday's vanguard surprised and crushed the great army of Yuri II, the Grand Prince of Vladimir, at the battle of the Sit River in 1238. He also participated in the Siege of Kiev in 1240. After the conquest of Rus, the Mongols invaded Eastern Europe and parts of Central Europe. His name appears as Bujgai or Bujakh in The Secret History of the Mongols. According to The Secret History of the Mongols, Ögedei, Khagan of the Mongol Empire, praised Subutai and Bujgai's merit when he criticized his son Güyük's arrogant behaviour during the campaign. Borolday assisted Subutai to prepare the strategy of the final assault during the Battle of Mohi (1241). Borolday's division directly attacked the main camp of King Béla IV of Hungary. Batu's brother Shiban's vanguard supported this attack. After a very hard fight, Batu's army crushed the Hungarians and their allies, Croats and Templar Knights at Mohi on April 11, 1241.

During the succession struggle over the throne of the Mongol Empire in early 1251, 100,000 Jochid troops under Borolday were stationed near Otrar to keep an eye on the Chagatayids who allied with the Ögedeids against Batu's cousin and ally, Möngke.

In 1255, Daniel of Galicia revolted against the Mongol rule. He repelled the initial Mongol assault under Orda's son Quremsa. Berke replaced Quremsa, son of his eldest brother, Orda, with the much experienced Borolday. The latter led a force that overcame the resistance of Danylo of Halych in 1259. According to some sources, Daniel fled to Poland leaving his son and brother at the mercy of the Mongol army. He may have hidden in the castle of Galicia instead. The Mongols needed to halt Poland's aid to Daniel as well as war booty to feed the demand of their soldiers. Boroldai forced him to demolish all walls of cities in Galich and Volhynia.[2] The Mongols knew that the Lithuanians had raided Mongol vassals, Smolensk and Torzhok, in the previous year.[3] Alongside Talabuga Khan and Nogai, Boroldai led a punitive expedition against the Grand Duchy of Lithuania. The Mongols attacked Lithuania, but the Lithuanians fled before the decisive battle. After pillaging several villages and towns in Lithuania, Borolday returned to Galich and demanded Daniel assist him in his battle against the Poles. The Rus soldiers under Daniel's son, Lev, and brother, Vasily, joined the Mongol expedition. Lublin, Sandomierz, Zawichost, Kraków, and Bytom were ravaged and plundered by the Mongol army. Berke had no intention of occupying or conquering Poland. After this raid Pope Alexander IV tried without success to organize a crusade against the Mongols.

After 1259, Boroldai's name does not appear again in Russian annals. A general named Burulday was killed in the battle at the Terek River on January 13, 1263, during the Berke–Hulagu war. This may have been Boroldai. His name appears in the opera The Legend of the Invisible City of Kitezh and the Maiden Fevroniya by Nikolai Rimsky-Korsakov, and in Mongolian fairy tales.

• Ж.Бор - Монгол хийгээд Евразийн дипломат шаштир боть 2
• Grousset, René (1970). The Empire of the Steppes: A History of Central Asia. New Brunswick, N.J: Rutgers University Press. ISBN 0-8135-0627-1.
• Rashid-al-Din Hamadani. Jami' al-Tawarikh ("Compendium of Chronicles")