As the Golden Horde was breaking up, he established himself in Crimea and spent most of his life fighting off other warlords.

He is said to have introduced the new state symbol, taraq tamğa, or "the trident of the Girays", which is derived from the scales insignia of the Golden Horde.

[5] Haji's grandfather was Tash-Timur bin Cansı and his father was Gyyas-ed-Din (Гыяс-эд-Дин, Gıyaseddin).

After Edigu's death in 1419, Devlet-Berdi and his nephew Haji Giray established themselves in Crimea.

Once Ulugh Muhammad launched his invasion of the area, many nobles changed sides, including the Shirin chief Tegene-Bey.

In 1434, Ulugh Mohammad once again invaded Crimea, the Shirins changed sides, and Haji fled to the Lithuanian lands to gather a new army.

He became unpopular when his officials greatly increased taxes and nomads several times raided the peninsula.

Around 1440 the Crimean nobles asked Casimir IV Jagiellon of Lithuania to release Haji.

He went to Kiev, met the Beys and went to Crimea with a large army joined by Radvila Astikas (the founder of the Radziwills) and drove out Sayid's governor.

In that year he minted coins with his name at Chufut-Kale, so 1441 is often taken as the official start of his reign and the foundation of the Crimean Khanate.

Haji, supported by the Shirins and Baryns entered Crimea and became khan (in August 1449?).

Haji allied with Alexios I of Theodoro (1410–1447), gave him financial and military support and sent troops to help him re-take Kalamita/Inkerman from the Genoese.

Next year a Turkish fleet (56 ships under Demir-Khyakhi) approached Crimea to raid the Genoese ports.

In 1456, Haji defeated Mahmud bin Küchük as he was crossing the Don after a raid on Russia.

Mahmud was replaced by his brother Ahmed Khan bin Küchük and fled to Astrakhan.

In 1475, the Turks captured the Genoese colonies on the south coast and in 1478 made Mengli I Giray (1478–1515) khan as a vassal or ally, an arrangement that lasted until 1774.

In 1523–1532 the khanate was contested by Mehmed's sons and brothers until Sahib I Giray (1532–1551) established a firm rule.