root word: ahon
nagsiahon: coming out from a river or going up a mountain (used for a lot of beings engaged in the action, not just one)
Umahon ang baka sa ilog.
The cow waded out of the river.
Nagsiahon ang mga baka sa ilog.
The cows waded out of the river.
From the Bible’s Old Testament… Genesis, Chapter 41
When two full years had passed, Pharaoh had a dream: He was standing by the Nile, when out of the river there came up seven cows, sleek and fat…
At narito may nagsiahon sa ilog na pitong bakang magagandang anyo at matatabang laman…