How to control the generation of large number of Agents?

Hi,
Design specification: we have data coming from 400 RF beams. These are stored in a FIFO, there is a dedicated location for each beam data means FIFO size is 400. To perform block level verification, we must drive beam data in parallel for all the locations of the FIFO. Easiest approach to drive the inputs is instantiate same Agent 400 times are run sequence of all agents in parallel. But maintaining such Testbench is difficult. In future we may have 1000 beams support. Please suggest how I can verify this block completely with the simple TB?
Regards,
Sudhanshu