This study discusses the dynamics of land tenure in Harapan Rainforest, Jambi, by the Indonesian Peasants Union (SPI) and the Batin Sembilan indigenous community to form a new commons in response to the pressures of agrarian capitalism, especially oil palm plantations and forest conservation. Based on ethnographic studies, this study reveals how the collaboration between SPI and the Batin Sembilan indigenous community created a new mechanism for collective forest management. This process involved land negotiations with customary leaders, the establishment of local rules, and solidarity that strengthened claims to customary forests. In addition, the collaboration between SPI and the Batin Sembilan indigenous community also encouraged the formation of new 'Adat' institutions that strengthened claims to forest resources but became an essential step in building a more inclusive and sustainable commons system. Thus, this study highlights how land tenure in Hutan Harapan serves as a meeting point between agrarian resistance and customary revitalization to create a new commons by offering a resource management model articulating social and ecological justice.