Jagoldai (Tatar Turkic: Cağolday, Cağalday, Polish: Jaholdaj, Jahołdajewszczyzna, Russian: Яголдаева тьма) (pronounce: yah-gohl-DAI or jah-ghahl-DAY) – little Tatar Turkic tyumen (duchy) in today Kursk Oblast and Belgorod Oblast of Russia as well as the Sloboda Ukraine, vassal of the Grand Duchy of Lithuania in 15th–16th century.

It was founded in 1438 by Tatars of Golden Horde.

• Turkic peoples
• Timeline of Turks (500-1300)

Tatar Encyclopaedia (in Tatar). Kazan: The Republic of Tatarstan Academy of Sciences. Institution of the Tatar Encyclopaedia. 2002. {{cite encyclopedia}}: Missing or empty |title= (help)