Based on Sri P.B. Annangaracharyar Swami's Commentary
Dhati Panchakam speaks of the victory of Ramanuja over other philosophies - both those that accept Vedas and those that don't - and his establishing the Visishtadvaita philosohpy that was built by Azhvars and Purvacharyas. As the name shows it is made of five shlokas. The word dhATI means "attacking" - as this work shows the attack that Ramanuja carried over the other philosophies that were widespread at that time, it is an appropriate name for it.
There are some who believe that the entire work was written by Swami Kooraththazhvan. While others believe that it was written by several disciples of Swami Ramanuja such as Kooraththazhvan, Mudhaliyandan, Embar and others. In either case, this work has been celebrated by our acharyas and has been included as part of Srivaishnava nithyanusandhanam.
This work as well as Ramanuja Chatusshloki - which was authored by another of Ramanuja's disciples, Thirumalai Anandazhavan - describe the triumphs of Ramanuja over other philosophies.