The MalaysiaâThailand border consists of both a land boundary across the Malay Peninsula and maritime boundaries in the Straits of Malacca and the Gulf of Thailand / South China Sea. Malaysia lies to the south of the border while Thailand lies to the north.he border between Thailand or Siam and the sultanates of the Malay Peninsula (Peninsular Malaysia today) has varied throughout history according to the influence the kingdom over the sultanates.