During this period, China was Thailand's top source of tourists.
The government is targeting 35 million foreign tourists in 2024, up from an estimated 28 million visitors last year.
The two countries have mutually waived visas with effect from March.
Vietnam received 1.51 million foreign tourists in January, up 10.3% from the previous month and 73.6% year-on-year and the highest monthly number since it reopened post-Covid.