Complex sentence: Hyvinkää village gradually grew in the latter half of the 19th century, though it was the construction of the railway network through Finland, beginning in 1861, that marked the starting point for the town's rapid growth.
Split into simpler sentences: Hyvinkää village gradually grew in the latter half of the 19th century. But it was the construction of the railway network through Finland, beginning in 1861, that marked the starting point for the town's rapid growth.