China's President Xi Jinping has vowed to make “proper arrangements” for Taiwan to join regional economic bodies and to solve longstanding political differences -- but only if Taiwan’s ruling party adheres to the “one China” principle, China's Xinhua News Agency reported. “The two sides can consult with each other on [an] equal basis under the principle of ‘one China,’ and reach a reasonable arrangement,” Xi was quoted as saying Monday in Beijing.

Xi, who heads China’s ruling Communist Party, met with Taiwan’s Nationalist Chairman Eric Chu on Monday in Beijing’s Great Hall of the People. It was the highest-level talk between the two sides of the Taiwan Strait in six years. But the warming relations between the leaders of longtime political rivals are controversial. Many Taiwanese who oppose reunification fear that joining economic bodies in Beijing would result in economic dependency on mainland China, BBC News said.

Here are five things to know about China-Taiwan relations:

1. The PRC has threatened military force if peaceful unification is ultimately rejected or official Taiwanese independence is declared, the U.S. Department of State’s Office of the Historian says.

2. The Republic of China (ROC), a nationalist government, lost the Chinese Civil War against the Communist Party in 1949. The nationalists fled to the island of Taiwan while the Communist Party took control of mainland China, establishing a sovereign state known as the People’s Republic of China (PRC).

3. The ROC currently governs Taiwan and surrounding isles as well as islands in the South China Sea. However, the PRC on mainland China refused to recognize the ROC as Taiwan’s governing body and has long claimed sovereignty over Taiwan as its 23rd province. Mainland China currently holds jurisdiction over 22 provinces.

4. The “one China” policy states that there is only one China of which Taiwan is an indivisible part, the Center for Strategic and International Studies says. The ROC has said Taiwan is a sovereign, independent country that does not come under mainland China. The United States officially adheres to the “one China” policy but has warned the PRC against coercive unification efforts.

5. In 1992, representatives from the PRC and ROC agreed to recognize there is only one China -- both mainland China and Taiwan belonging to the same state. However, each side could have its own interpretation of the meaning. The two countries disagree on which is the legitimate government of this one China.