The Vietnamese court discovered the Song's secret attempt to ally with Champa; while Dai Viet sent a delegation to Yongzhou to thank Song for putting down local rebellions and to negotiate terms of peace, they instructed their agents to gather intelligence on the alleged Champa alliance and the strength of Song's military presence in the Guangnan Western Circuit. Two Vietnamese envoys were permitted to offer tribute to the court of Renzong in Kaifeng, arriving on 8 February 1063 to deliver gifts, including nine tamed elephants. On 30 March 1063, Emperor Renzong died and was succeeded by Emperor Yingzong (r.1063–1067); Vietnamese envoys arrived in Kaifeng again to congratulate Yingzong on his ascension, and on 7 April 1063, Yingzong sent gifts such as calligraphy works by Renzong to Vietnamese King Lý Thánh Tông. On the day that the Vietnamese envoy Lý Kế Tiên prepared to depart from Kaifeng back to Đại Việt, news arrived that Thàn Thiệu Thái had raided Song's Guangnan West Circuit again. Although a plea from a Guangnan official urged Kaifeng to take action, Yingzong left defenses up to local Guangnan forces and labeled Thàn Thiệu Thái as "reckless and mad" in an effort to disassociate him from the Lý court.