Complex sentence: The cards were typically used by the lower class to play gambling games, and were intended to be easy and cheap to make because, as gambling was illegal in China, there was a need for cards that could be disposed off easily.
Split into simpler sentences: The cards were typically used by the lower class to play gambling games, and were intended to be easy and cheap to make. This is because gambling was illegal in China and there was a need for cards that could be disposed off easily.