The ex-president is visiting in a private capacity, bringing a delegation of academics and college students for exchanges, as well as members of his family, but the trip is loaded with political meaning.

Ma’s policies brought Taiwan and Beijing to their closest relationship ever, but his exit from office was overshadowed by massive protests against a trade deal with the mainland and his successor has focused on defending the autonomy of the democratically-governed island that China claims as part of its own territory.

Ma’s visit comes amid rising tensions. Beijing has exerted a long-standing campaign of pressure against Taiwan, poaching its diplomatic allies while also sending military fighter jets flying toward the island on a near daily basis. On Sunday, Honduras established diplomatic relations with China, leaving Taiwan with only 13 countries that recognize it as a sovereign state.

Ma, a member of the opposition Nationalist Party (Kuomingtang), will land in Shanghai before starting his visit in nearby Nanjing. He is expected to tour the mainland from March 27 to April 7, stopping in Wuhan and Changsha, as well as other cities. He is bringing college students from Taiwan to meet with fellow students from Shanghai’s Fudan University and Changsha’s Hunan University.

Ma has framed the visit as a bid to lower the tensions in cross-strait relations through people to people exchange. “I hope through the enthusiasm of the youth and their interactions to improve the cross-strait mood, so bring peace faster, and earlier,” he said to reporters ahead of his departure on Monday afternoon. He also said it would be his first time visiting China.

His trip has not drawn much controversy in Taiwan, where the public is used to seeing Kuomingtang politicians visit China. However, it has been criticized by some political opponents and activists.

A former mainland student leader in the 1989 Tiananmen square protests called on Ma to cancel his trip. “If you have even a strand of affection for Taiwan ... you should announce the cancelation of your trip,” said Wang Dan, a Chinese dissident who previously lived in Taiwan, on his Facebook page.

A handful of protesters from a pro-independence group held a demonstration at the departures area at Taoyuan airport before Ma’s departure. “Ma Ying-jeou is humiliating our nation and forfeiting its sovereignty,” they shouted before police carried them out. “You are a stinky beggar.”

On the other side, a small group of people from the pro-unification camp also came to the airport to show their support. “Cross-strait relations are like flowers blossoming in spring and both sides are a family,” they shouted.

The trip is also a chance for him to honor his ancestors, ahead of Tomb Sweeping Day on April 5. During the festival, which is celebrated in Taiwan and China among other countries, families visit ancestral graves to maintain the burial grounds and remember the dead.

Ma will not go to Beijing, but may meet with Chinese officials.

Ma met with Chinese President Xi Jinping in Singapore in 2015, while he was still in office. The meeting was the first between the leaders of the two sides since Taiwan split from mainland China in 1949 during the Chinese civil war, but was considered more symbolic than substantive.

In 2016, the independence-leaning Democratic Progressive Party won national elections and Beijing cut off contact with Taiwan’s government, citing President Tsai Ing-wen’s refusal to endorse the idea that Taiwan and China are one country.