By the time Ashraf reached and besieged Semnan his force had grown to 40,000 compared to Nader's estimated strength of 25,000. Leaving a token force behind to resume the siege of Semnan Ashraf marched east towards Shahroud sending a fraction of his command ahead to seek out and destroy Nader's artillery. The first clash of arms between the two side occurred in a small but savagely fought skirmish south-east of Shahroud in which 14 Afghans were made prisoners whom were taken to Nader for interrogation. Nader continued to press forward until dusk, whence he began to make camp east of an obscure village by the name of Mihmandoost. That night Tahmasp promised him his sister's hand in marriage if Nader gained victory in battle on the following day.