Jagoldai (Tatar: Җагалдай, Cağolday, Cağalday; ; , Yagoldayeva t'ma; pronunciation: or ) was a small Tatar tumen (territorial and military-administrative unit) in what is now Kursk Oblast and Belgorod Oblast of Russia, as well as parts of Sloboda Ukraine. It existed as a vassal state of the Grand Duchy of Lithuania during the 15th and early 16th centuries.
The principality was founded between 1428 and 1438 by Tatars who had defected from the Golden Horde during a period of internal strife and plague. The Russian designation t'ma (тьма, literally "darkness") derives from the tumen, a Mongol-Tatar administrative unit theoretically representing 10,000 households or soldiers.
History
Foundation
The period between 1428 and 1430 was marked by severe instability in the Golden Horde. According to the Nikon Chronicle, there was "strife and great turmoil" (Бысть брань и замятия вели) among the Tatars, accompanied by an epidemic of plague that killed large numbers of people. A yarlig (decree) from the Crimean Khan Meñli I Giray later referred to the territory as "the tumen of Jagoldai, son of Saray" (Сараева сына Егалтаеву тму), confirming the transmission of the territory to the Grand Duke of Lithuania.
The Polish historian Stefan Kuczyński, who wrote one of the most detailed studies of Jagoldai, localised the principality to the upper reaches of the Oskol River, connecting it with a settlement called "Jagoldai gorodishche" (Jagoldai fortified town) that existed in the 17th century.
Decline and absorption
In the second half of the 15th century, the principality was ruled by Roman Jagoldaevich, who was either the son or great-grandson of the founder Jagoldai Sarayevich.
A 1600 survey mentioned that in 1570, there were "Oskol Cossacks" (оскольские казаки) in the region.