Abu Zakariyya Yahya ibn Umar ibn Talagagin ibn Turgut ibn Wartasin, commonly suffixed al-Lamtuni al-Sanhaji, (d. near Azuggi, 1056; Arabic : يحيى إبن عمر) was a chieftain of the Lamtuna, a tribe in the Sanhaja confederation. Yahya ibn Umar was the second emir of the Almoravids in the mid-11th century, a movement his predecessor, Yahya Ibn Ibrahim, constructed in collaboration with the religious leader Abdallah ibn Yasin. Yahya led the Almoravid armies in their first campaigns, including captures of Sijilmassa and Awdaghost in 1054/55, but was himself killed in battle against a dissident Berber faction in the Adrar. Yahya was succeeded as Almoravid emir by his brother, Abu Bakr ibn Umar.