The Military Territory of Niger was subsequently created within the Upper Senegal and Niger colony (modern Burkina Faso, Mali and Niger) in December 1904 with its capital at Niamey, then little more than a large village. The border with Britain's colony of Nigeria to the south was finalised in 1910, a rough delimitation having already been agreed by the two powers via several treaties during the period 1898–1906. The capital of the territory was moved to Zinder in 1912 when the Niger Military Territory was split off from Upper Senegal and Niger, before being moved back to Niamey in 1922 when Niger became a fully-fledged colony within French West Africa. The borders of Niger were drawn up in various stages and had been fixed at their current position by the late 1930s. Various territorial adjustments took place in this period: the areas west of the Niger river were only attached to Niger in 1926–27, and during the dissolution of Upper Volta (modern Burkina Faso) in 1932–47 much of the east of that territory was added to Niger; and in the east the Tibesti Mountains were transferred to Chad in 1931.