Dear Student
The Ashvamedha or horse sacrifice" was considered as one of the most important royal rituals.This yagna should be conducted only by a king.
A horse was let loose to wander free and was guarded by men of raja. If the horse wandered in kingdoms of other rajas and they stop it and they have to fight. If they allowed horse to pass, it meant that they accepted that the raja who wanted to perform the sacrifice was stronger than them. These rajas were invited to the sacrifice, which was performed by specially trained priests who were given gifts.
Its main idea or object was to acquire power, fame, control over neighbouring provinces, and general prosperity of the kingdom.
Regards