Montgomery moved to Brighton in 2005 and, following the break-up of Amityville, embarked on a collaboration with Keris Howard, formerly of the band Harper Lee.
Đông Sơn influence is seen throughout Southeast Asia, from the moko drum of Alor in Indonesia, which are suspected of originating with Đông Sơn bronze drums, to the design of keris knives.
Keris Mas was one of the 19 founding members (comprising teachers and journalists) of the movement, which includes Usman Awang, Abdul Samad Ismail, Masuri SN and others.