Final answer:
The Ta-p'en-k'eng culture was known for domesticating pigs, which played a crucial role in their agricultural society in modern Thailand.
Step-by-step explanation:
The domesticated animal associated with the Ta-p'en-k'eng culture is the pig. This agricultural society, based in what is now modern Thailand, established complex farming and livestock management systems, distinguishing itself with the deliberate domestication of various plants and animals significant for subsistence. The Ta-p'en-k'eng culture is noted for cultivating different roots like taro and yams, and for domesticating pigs and poultry, which played a crucial role in their society.