The “special relationship” between Thailand and the PRC predates the Thaksin era. Its origins lie in the mid-1970s when, after over two decades of mutual hostility, the two countries established formal diplomatic relations in July 1975. In 1979, the relationship was transformed when the two countries forged a de facto alliance in opposition to Vietnam’s occupation of Cambodiaand (here)
China and Thailand essentially formed a de facto alliance that ultimately extended to the armed forces of the two countries. China and Thailand signed a "Strategic Partnership" arrangement, which has included a regular exchange of military personnel and exercises. Since the early 1980s, Thailand has purchased armaments and military-related equipment under this partnership at "friendship prices" – much of which has effectively amounted to military gift aid. China and Thailand have announced a whole raft of measures and initiatives to mark the thirtieth anniversary of formalized relations in the year 2005
Anyways, it is all water under the bridge now.