California by the United States, the region's Indigenous Californian population plummeted from around 150,000 to around 30,000 due to disease, famine, forced removals, slavery, and massacres. Many historians refer to the massacres as the California genocide. Between 9,500 and 16,000 California Natives were killed by both government forces and white settlers in massacres during this period. Despite the well documented evidence of the widespread massacres and atrocities, the public school curriculum and history textbooks approved by the California Department of Education ignore the history of this genocide. According to author Clifford Trafzer, although many historians have pushed for recognition of the genocide in public school curricula, government-approved textbooks omit mention of the genocide because of the dominance of conservative publishing companies with an ideological impetus to deny the genocide, the fear of publishing companies being branded as un-American for discussing it, and the unwillingness of state and federal government officials to acknowledge the genocide due to the possibility of having to pay reparations to indigenous communities affected by it. War crimes Japanese war crimes The post-war minimization of the war crimes of Japanese imperialism is an example of "illegitimate" historical revisionism; some contemporary Japanese revisionists, such as Yūko Iwanami (granddaughter of General Hideki Tojo), propose that Japan's invasion of China, and World War II, itself, were justified reactions to the racist Western imperialism of the time. On 2 March 2007, Japanese prime minister Shinzō Abe denied that the military had forced women into sexual slavery during the war, saying, "The fact is, there is no evidence to prove there was coercion". Before he spoke, some Liberal Democratic Party legislators also sought to revise Yōhei Kōno's apology to former comfort women in 1993; likewise, there was the controversial negation of the six-week Nanking Massacre in 1937–1938. Shinzō Abe was general secretary of a group of parliament members concerned with history education (Japanese: 日本の前途と歴史教育を考える若手議員の会) that is associated with the Japanese Society for History Textbook Reform, and was a special advisor to Nippon Kaigi, which are two openly revisionist groups denying, downplaying, or justifying various Japanese war crimes. Editor-in-chief of the conservative Yomiuri Shimbun Tsuneo Watanabe criticized the Yasukuni Shrine as a bastion of revisionism: "The Yasukuni Shrine runs a museum where they show items in order to encourage and worship militarism. It's wrong for the prime minister to visit such a place". Other critics note that men, who would contemporarily be perceived