Hong Kong was a British protectorate from 1841 when it was ceded to the United Kingdom by China. In 1997, Hong Kong Island, Kowloon Peninsula and the New Territories on the mainland were returned to Chinese sovereignty, and became the Hong Kong Special Administrative Region (SAR) of China. In this agreement, China promised that, under its "one country, two systems" formula, Hong Kong will enjoy a high degree of autonomy in all matters except foreign and defence affairs for a period of 50 years. Hong Kong has a thriving economy, based on international trade. It contributes to, and benefits from China's rapidly developing economy. The churches are a minority, but very active in social work and evangelism. Many churches and Christian organizations have significant links with partner churches and agencies in mainland China. There has been renewed commitment to the issue of poverty and the area of education in Hong Kong. About half of the Protestant churches belong to the Evangelical, Pentecostal, and Holiness traditions. For several years now there has been a Metropolitanate of the Ecumenical Patriarchate (Eastern Orthodox) in Hong Kong, which covers South East Asia. As an international city, Hong Kong has also many foreign language congregations. The Hong Kong Christian Council is the ecumenical body.