Viharas were for the purpose of living, Chaityas were assemblies for the purpose of discussions. Further, Chaityas were with Stupas, Viharas did not have stupas.
The Ikshavakus rose in the Krishna-Guntur region on the ruins of Satvahanas. The Ikshavakus were a local tribe. They started the practice of land grants in the Krishna-Guntur region. They also built many monuments.