On Sept. 29, 1972, Japan normalized diplomatic relations with China. It has now been 45 years since that milestone, and bilateral relations have seen some colossal changes. Over the years, documents have been prepared to accommodate those changes: the Japan-China Treaty of Peace and Friendship of 1978, the Japan-China Joint Declaration of 1998, and the Japan-China Joint Statement on Comprehensive Promotion of a "Mutually Beneficial Relationship Based on Common Strategic Interests," which was issued in 2008. Together with the Japan-China Joint statement of 1972, these constitute the so-called four basic documents of Sino-Japanese relations. Adding to them is the four-point consensus recently agreed between the Shinzo Abe and Xi Jinping administrations, another document seen as outlining the basic provisions for diplomatic ties between China and Japan.
Diplomatic relations between the two Asian powers have changed markedly over the course of the past 45 years. For one thing, the point in 2010 when China's GDP exceeded that of Japan was surely a development of significant moment. Although Japan's GDP per capita still exceeds that of China, there is clearly a limit to the growth of Japan's economic power, and the difference in per capita GDP between China and Japan will continue to shrink for the foreseeable future. This has given the impression of a shift in the balance of power between the two countries.
Second, there are the changes that have taken place in the international environment. The normalization of Japan-China relations came during the Cold War. As an internal conflict began to occur within the Eastern Bloc between China and the Soviet Union, China began to reach out the United States; a development which in some aspects also served to encourage the normalization of diplomatic relations with Japan. Later, the Cold War drew to an end and the Soviet Union was dismantled, but in East Asia, the U.S. and China faced off, drawing their dividing lines across the Korean Peninsula and the Taiwan Strait.