Prior to the foundation of the United Republic of Nations, the Fire Nation was the most technologically advanced when it came to manufacturing weapons. This was due to their initiation of and dominant role in the Hundred Year War. The Earth Kingdom is the second most proficient due to the necessity of defending itself against the industrially superior Fire Nation, especially after the crumbling of the Southern Water Tribe. Both the Northern and Southern Water Tribes are capable of crafting their own weapons, which are often made of sharpened metal or animal parts such as skins and teeth.