Umar ya yanke shawarar buge Farisawa nan da nan bayan sun sha kashi a Nahavand, alhali yana da fa'ida ta hankali.Dole ne Umar ya yanke shawarar farko a cikin larduna uku: Fars a kudu, Azarbaijan a arewa ko Isfahan a tsakiya.Umar ya zabi Isfahan ne, kasancewar ita ce cibiyar daular Farisa, kuma mashigar samar da kayayyaki da sadarwa a tsakanin dakarun Sassanid , kuma kama shi zai mayar da yankin Fars da Azarbaijan saniyar ware daga Khorasan, tungar Yazdegerd.Bayan ya ci Fars da Isfahan, za a kai hare-hare na gaba a lokaci guda kan Azarbaijan, lardin arewa maso yammacin kasar, da Sistan, lardin gabas na Daular Farisa.Cin waɗannan lardunan zai bar Khorasan saniyar ware kuma mai rauni, mataki na ƙarshe na cin nasarar Farisa Sassanid.An kammala shirye-shirye a watan Janairun 642. Umar ya nada Abdullahi bn Uthman a matsayin kwamandan dakarun musulmi domin yakar Isfahan.Daga Nahavand, Nu'man bn Muqaarin ya zarce zuwa Hamadan, sannan ya zarce kilomita 370 (mil 230) kudu maso gabas zuwa birnin Isfahan, inda ya fatattaki sojojin Sasaniya a can.An kashe kwamandan makiya Shahrvaraz Jadhuyih tare da wani janar na Sasaniya a lokacin yakin.Nu'uman, tare da wasu sabbin dakaru daga Busra da Kufa a karkashin jagorancin Abu Musa Ashaari da Ahnaf bn Qais suka yi wa garin kawanya.An ci gaba da killace har na wasu watanni kafin birnin ya mika wuya.