Until this day, the Indigenous community experienced the legacy of colonization. Yet, current research on British settler colonialism lacks an emphasis on how the treaty-making process consolidated the oppressive colonial power dynamics. By comparing the treatymaking approaches of the British Empire in New South Wales, Australia and Aotearoa New Zealand, my thesis explores how the absence and presence of treaties shaped complex and evolving relationships between Indigenous groups and colonial powers. It investigates the inconsistency of the British treaty making approach in settler-colonial territories by examining the abandonment of treaty-making in Australia in the 1780s and the reinstatement of treaty-making diplomacy in Aotearoa New Zealand between the 1830s to 1840. By narrating both the Indigenous and colonial perspectives on a transnational scale, it compares how first encounter and geopolitical factors contributed to a shift in colonial diplomatic strategies and the evolution of colonial expansion. It will also examine the legacy of the colonial era by comparing land and assimilation policies in the 19th and 20th centuries. Overall, it demonstrates that in the short term, the absence and presence of treatymaking subjugated Indigenous sovereignty and land rights both in Australia and Aotearoa New Zealand. However, treaty-making impacted the long-term reconciliation and decolonization framework. This research will contribute to a better understanding of the historical and ongoing impacts of colonialism on Indigenous communities in Oceania and potentially assist policymakers in developing reconciliation strategies.