I want to know the answer to the following question:
When did Emperor Huan's reign begin?
All the background I'm provided with is that "A Roman embassy of Emperor Marcus Aurelius (r. 161–180 AD) is recorded in the Hou Hanshu to have reached the court of Emperor Huan of Han (r. AD 146–168) in AD 166, yet Rafe de Crespigny asserts that this was most likely a group of Roman merchants.". Is that enough to answer the question?