Acacias are widely grown plantation trees that are extensively planted in China, India, Indonesia, Malaysia, the Philippines, Thailand and Vietnam; there are approximately two million hectares planted worldwide. The plants are very useful for many different purposes. Research on tripartite association of arbuscular mycorrhizal fungi, Rhizobium and Acacias for restoration of ecosystems is very limited throughout the world particularly in Saudi Arabia. There is a growing need to find out ways and means to reduce the problem of desertification in order to rehabilitate and increase plant diversity of degraded rangelands in Saudi Arabia.  Arbuscular Mycorrhizal Fungi (AMF) is widespread throughout the world and is found in the majority of terrestrial ecosystems including plants in arid and semiarid regions. They can improve plant growth by up taking P, N, K, Ca, S, Cu, Mn and improving water absorption; enhance the salt tolerance; improve soil aggregates and plant diversity along with other benefits. Rhizobium, beneficial soil bacteria, is useful for N fixation and also other benefits to the Acacias. Although AM fungi and Rhizobium are important to the persistence of vegetation in harsh environment, little is known about the diversity of these beneficial symbioses in rangelands ecosystems and their beneficial role for the sustainable management of arid and semi-arid ecosystems. Here we have explored the present status of research on AMF and Rhizobium with Acacias and their need for rehabilitation of rangeland ecosystems to reduce the desertification in Saudi Arabia. The interactive effects of AMF and Rhizobium under both saline and drought stress conditions on growth of Acacias and their out planting performance in association with green manure mycotrophic plants under field condition are some of the innovative ideas which are urgently needed for successful restoration of rangeland ecosystems in Saudi Arabia to reduce the desertification.