The development of the weapon was lengthy as it involved the establishment of an adequate industrial structure to support it.[2] Before producing local weapons, the early Imperial Japan Army had been relying on various imports since the time of the Boshin War, and especially on the French Chassepot, the British Snider-Enfield and the Spencer repeating rifle.[2] This was about 300 years after Japan developed its first guns, derived from Portuguese matchlock designs, the Tanegashima or "Nanban guns".