My unsorted thoughts:

Maybe it was a slave revolt.

• pro: people from different settlements. Stolen at some point and brought to the same place where they revolted and were beaten down.
• contra: who would give them offerings and bury them with respect?

Maybe it was the supply train of an army that was also killed after the defeat of said army.

• pro: mostly women
• contra: why the tribal diversity? Was it a battle of the five armies style train?

Maybe a treck of refugees as someone else commented.