In my opinion, China market is one of the reasons which made Bitcoins price down. In fact, price declines strong because many people sell it too much. There are 2 cases: firstly, the big investors feel Bitcoin has risen enough and may make a profit, so they simultaneously sell. Secondly, there is an exchange that is hacked and stolen Bitcoin.
Thirdly, cryptocurrency exchanges in china use kinds of unfair ways to trade coins that common traders hold.for example fake data instead of real coin.