The semi-arid regions of eastern Indonesia are major contributors to the national beef supply but face persistent feed shortages during prolonged dry seasons. Over the past four decades, the introduction and adaptation of various forage legume species-ranging from tree, shrub, to herbaceous types-have played a vital role in improving feed quality and livestock productivity. The introduction of Leucaena leucocephala in the 1920s and its subsequent expansion in the 1970s significantly transformed the Amarasi cattle fattening system in West Timor. However, the psyllid (Heteropsylla cubana) outbreak in the mid-1980s triggered extensive evaluation of resistant and alternative species such as Leucaena leucocephala cv. Tarramba, Gliricidia sepium, and Acacia angustissima. Parallel trials identified highly adaptable herbaceous and shrub legumes, including Clitoria ternatea, Centrosema pascuorum, Pueraria phaseoloides, Vigna luteola, Desmanthus virgatus, Stylosanthes seabrana, and Desmodium rensonii. This review synthesizes more than forty years of research and field experience through a systematic literature search using Scopus, Google Scholar, and ScienceDirect, complemented by expert field observations and AI-assisted synthesis for enhanced organization and verification. Despite high adaptability and nutritional potential, the adoption of forage legumes by smallholders remains limited due to seed scarcity and technical constraints. Successful models such as the Leucaena-based Amarasi system and legume supplementation strategies have proven effective in improving cattle performance and reducing calf mortality. Future opportunities include the development of community-based seed systems, drone-assisted oversowing, and wider integration of legumes into climate-resilient farming systems.