sentences:  He had already launched an expedition against Kerman in 1719 and in 1721 he besieged the city again.Failing in this attempt and in another siege on Yazd, in early 1722, Mahmud turned his attention to the shah's capital Isfahan, after first defeating the Persians at the Battle of Gulnabad.Rather than biding his time within the city and resisting a siege in which the small Afghan army was unlikely to succeed, Sultan Husayn marched out to meet Mahmud's force at Golnabad.