Koreans from throughout the Japanese Empire back to the Korean Peninsula were characterized both bureaucratically and popularly as "repatriation", a restoration of the congruence between the Korean population and its territory. The pre-colonial Korean state had not clearly laid out the boundaries or criteria determining who was a citizen; however, the Japanese colonial government had registered all Koreans in a separate family registry, a separation which continued even if an individual Korean migrated to Manchuria or Japan; thus North and South Korea had a clear legal definition of who was a repatriating Korean, and did not have to create any special legal categories of national membership for them, the way Germany had done for post-World War II German expellees. There has also been a return migration of Korean Brazilians back to Korea, spurred by the increasing violence in Brazil. The largest-scale repatriation activities took place in Japan, where Chongryon sponsored the return of Zainichi Korean residents to North Korea; beginning in the late 1950s and early 1960s, with a trickle of repatriates continuing until as late as 1984, nearly 90,000 Zainichi Koreans resettled in the reclusive communist state, though their ancestral homes were in South Korea. However, word of the difficult economic and political conditions filtered back to Japan, decreasing the popularity of this option. Around one hundred such repatriates are believed to have later escaped from North Korea; the most famous is Kang Chol-Hwan, who published a book about his experience, The Aquariums of Pyongyang. South Korea, however, was a popular destination for Koreans who had settled in Manchukuo during the colonial period; returnees from Manchukuo such as Park Chung-hee and Chun Doo-hwan had a large influence on the process of nation-building in South Korea. Until the 1980s, Soviet Koreans did not repatriate in any large numbers and played little role in defining the boundaries of membership in the Korean nation. However, roughly 1,000 Sakhalin Koreans are also estimated to have independently repatriated to the North in the decades after the end of World War II, when returning to their ancestral homes in the South was not an option due to the lack of Soviet relations with the South and Japan's refusal to grant them transit rights. In 1985, Japan began to fund the return of Sakhalin Koreans to South Korea; however, only an additional 1,500 took this offer, with the vast majority of the population remaining on the