There is very little information about the past of the Siikainen parish in old documents. However, one document from the Middle Ages tells us the story of a fisherman's son from Mouhijärvi, named Otamo. He settled on the shore of a fishy water, and the oldest village in Siikainen, Otamo, is named after him. The area was named Siikainen after the fish-rich waters of the time, where whitefish were caught in abundance, among other things.
The independence of the municipality of Siikainen was prolonged by three consecutive drought years, when frost destroyed crops in the fields. Even grain had to be used as food and thatched roofs had to be torn down to feed animals. The so-called famine years, which were very destructive for the people, lasted three years (1866-1869). During this time, infectious diseases also raged among the people weakened by hunger. After the famine years, good harvests began to be obtained again. There was enough food to feed the hungry mouths again, and the population grew rapidly as the birth rate increased. Although infant mortality was high at that time, Siikainen was spared the greatest devastation caused by infectious diseases thanks to its remote location. The persecutions of the Great Wrath did not reach Siikainen too much.