This book is an in-depth research on the positive role of United Nations Organization, African Union and economic community of West African States on the attainment of peace in the world. The world is facing a lot of crises, yet; we have to believe that "All men are brothers, the doctrine of the unity of mankind, is absolute essential" The scholars and lovers of peace will gain a lot positively from this book: "Legacy of Peace in the World", Read it and say peace to the world. say 'No' to conflicts and wars. Peace shall reign in the world. 'Amen'.