The oldest dated
autochthonous rocks are Upper Carboniferous and Lower
Permian limestones with fusulinids and conodonts. The Lower
Permian microfossils are similar to South and North China and
do not have affinities with those of west Malaya or Thailand
(Vachard, 1990). Middle and Upper Permian and Early Triassic
sedimentary rocks appear to be absent.