Not common, a contract is required in Hong Kong. Now someone will say verbal contracts are a go, but I don't know anyone without a written contract. Plus you would lose (or make difficult to assert) your rights and protections without a written contract.
Did you ask when is your start date?
You can always follow up by email.
Hi xxx,
I'm looking forward to joining the team. Has there been any progress internally on the contract.
Looking forward to your reply.
Kind regards,
Xxx
**remember if they want you on the team, then it would be difficult to do anything stupid, except complain about the contract. So don't be worried to follow up. But don't call them every hour either. Once every 3-5 days is the most for follow up.
You also want to work for a company that replies to your emails. Needs to be a mutual relationship otherwise just a means to end.