Thailand has long been a hub for people trafficking, with thousands of Rohingya boat people from neighbouring Myanmar believed to have passed through the kingdom in recent years.
Police said the 200 refugees identified themselves as Turkish and were detained during a raid on a camp in a mountain rubber plantation on Wednesday night in Songkhla.
"It's an unprecedented case, that there are so many Turkish people arrested here," Pol Maj Gen Thatchai Pitaneelaboot, chief of the Immigration Bureau's Division 6, said by telephone.
"They came as families and it looks like they wanted to go somewhere else because they kept their belongings ready to move," he said. Several people believed to be "minders" had fled during the raid.
It was unclear how they arrived in Thailand. Police were waiting for an interpreter to help question the detainees, who have not yet been charged with any crime.
The Turkish embassy said it had no information about them, while the United Nations refugee agency did not immediately respond to a request for comment.
In January Thailand detained more than 500 Rohingya refugees after a raid on a suspected people-trafficking camp in its deep south, a Muslim-dominated region plagued by a nearly decade-long insurgency.
Thousands of Rohingya, described by the UN as among the world's most persecuted minorities, have fled sectarian violence in western Myanmar in rickety boats since 2012, mostly believed to be heading for Malaysia.
Thailand said last year it was investigating allegations that some army officials in the kingdom were involved in the trafficking of Rohingya.