Bandar Seri Begawan, with a population of about 100,000, is the capital of Brunei as well as its educational and cultural center. The city is located in the north of Borneo on the coastal plain of the southwest corner of Brunei Bay, and by Brunei River. With the rapid development of its oil economy, Brunei has become a modern city. The Tomb of the King of Boni in the early 15th century, located in Yuhuatai District of Nanjing, is one of the only two existing tombs of foreign kings in China. In November 2011, under the witnesses of Premier Wen Jiabao and the Sultan of Brunei, Hassanal, Nanjing and Bandar Seri Begawan established sister-city relationship. In November 2018, witnessed by President Xi Jinping and the Sultan of Brunei, Hassanal, Nanjing and Bandar Seri Begawan renewed the sister-city agreement, which was included in the China-Brunei joint statement.
In recent years, Nanjing has invested about RMB 20.28 million to renovate the surrounding environment of the original Tomb of the King of Boni, and built the Memorial Park of the King of Boni, the King of Boni Historic Exhibition Hall and China-Brunei Friendship Hall. Her Royal Highness Princess Hajah Masna, Ambassador-at-Large of the Ministry of Foreign Affairs, visited Nanjing three times in 2006, 2008 and 2019 respectively and attended the opening ceremony of China-Brunei Friendship Hall and the unveiling ceremony of the King of Boni Historic Exhibition Hall.
Since 2014, Brunei has invited Dragon Boat delegations from Nanjing four times to participate in its annual Regatta and relevant activities.