Final answer:
China was reunified under Tang Taizong through a combination of military campaigns, diplomatic successes, and the integration of cultural elements into a new, pluralistic empire. Tang's foreign policy, including the reestablishment of Chinese rule over Korea and the opening of relations with Japan, facilitated this process. Despite military setbacks, successful campaigns in the West and the Tang-Silla alliance contributed to Taizong's unification of China.
Step-by-step explanation:
Reunification of China Under Tang Taizong
The reunification of China under Tang Taizong was a multifaceted process that involved both military conquest and the integration of cultural elements into a new, pluralistic empire. Following the Sui Dynasty, Tang Taizong, also known as Li Shimin, seized power through a coup d'etat in 618 and embarked on a series of reforms and military campaigns to unify the region. The Tang dynasty fostered marriages across regional and linguistic lines to consolidate power and integrate the deeply divided northern and southern territories.
Tang Taizong's foreign policy earned early successes, such as reestablishing rule over Korea and opening diplomatic relations with Japan, which led to the Japanese adoption of Tang institutions and culture during their "Great Reform." While Tang Taizong experienced military setbacks, notably the humiliating defeat at Koguryo, his campaigns in the West were more successful. This balance of diplomacy and military might, along with embracing a pluralistic approach to governance, helped in the eventual unification of China under Tang Taizong's rule.
Furthermore, the Tang-Silla alliance resulted in both the Tang dynasty and Silla adopting similar administrative systems, which aided in the contending of centralized power. Despite cultural differences and the autonomy of regional rulers, the alliance and its subsequent reforms made the regimes of East Asia appear more uniform than they had been previously.