Complex sentence: The majority of Cilfynydd's housing and public buildings were built between 1884 and 1910, with this fast development necessary, as by 1891 the population had increased fivefold to over 500.
Split into simpler sentences: The majority of Cilfynydd's housing and public buildings were built between 1884 and 1910. This fast development was necessary, as by 1891, the population had increased fivefold to over 500.