 Complete the following phrase:  Abu Hafs was the grandson of the famous emir Umar ibn Abdallah al-Aqta his name is also transcribed as Amr ibn Ubaydallah, who was the ruler of the city of Malatya from the 830s until his death at the Battle of Lalakaon in 863. Under Umar, Malatya had been one of the most important emirates on the border zone thughur between the Abbasid Caliphate and the Byzantine Empire, and Umar himself had been one of the most active Muslim leaders in the perennial raids and counter-raids that characterized the 