I think a large part of this is because many Asian countries together publish the relevant policies on the prohibition of bitcoin trading, which gives investors a big blow.
that was mostly FUD and only partly true.
some Asian countries like China banned ICOs which have nothing to do with bitcoin and bitcoin trading. and most of them regulated exchanges with some restrictions on them to prevent illegal activities such as money laundering. again it had nothing to do with bitcoin trading or bitcoin itself.
but the media loves bullshit like this, and they exaggerate it. and most people don't care enough to check the source of the news they just read on a trollbox that "china banned bitcoin" and start panicking.