Although they quantitatively only take a marginal place amongst domestic herbivores (only 0.4% of world domestic herbivores), the large camelids (dromedary and Bactrian) are present in almost all the arid lands of the old world (except in Southern Africa), a widespread area of over 35 millions km². They are overall remarkable enhancer of these spaces by their productive potential and by their role in the agro-ecosystemic balance of the arid lands, especially with the current climatic changes. Elsewhere, they are known for their physiological peculiarities linked to their adaptation ability to harsh conditions of the desert and of its margin. In consequence, they represent a fabulous biological model for the scientists from different disciplines. Their place in the “modern world” has to be re-evaluated by considering these trends and these particularities.