First dual between Sugriva and Vali took place on 21 September 12210 BCE.
A lone astronomy reference exists for this particular dual
Valmiki described this fight between two brothers, as they rushed towards each other, as if to finish the fight before impending sunset, and compared them to a clash between Mercury and Mars.
If we simulate the western sky, immediately after sunset, for 21 Septemeber 12210 BCE (using Voyager 4.5), we find:
(I simulated for Delhi as location. More appropriate location would be Hampi/Bellary in Karnataka. This is for the benefit of archeo-astronomy enthusiasts, who would want to simulate in order to test)
Sun went below horizon at 8:05 PM
At 8:10 PM, Mars and Mercury were still above the horizon and their locations, along with that of the Sun (in Right Ascensions, Dynamic Epoch) were:
Mars – 6 hr, 50 min 42 sec
Mercury – 6 hr 49 min 33 sec
Sun (below horizon) – 6 hr 32 min 57 sec
If one simulates the same with change of location (e.g. Bangalore, Karnataka, India)
The sun was at the horizon at 7:30 PM and both Mars and Mercury were still above western horizon at 7:40 PM.