The early history of human settlement at Aldabra is obscure. Voeltzkow (1897) summarizes early knowledge, mainly from the charts in A. Grandidier’s Histoire physique, naturelle et politique de Madagascar (1885) from the sixteenth century onwards. It is possible that the atoll was visited by Arab or even Chinese seafarers before this time, for there was a flourishing trade on the East African coast, and the Arabs knew the Comoros, Madagascar and probably the Mascarenes (Hourani 1951; Freeman-Grenville 1962; Toussaint 1961). Apart from a single, probably Islamic, sherd on lie Picard, however, no archaeological remains of such visits have been found, and the only fragment of Chinese pottery, found in Passe du Bois, is nineteenth century (Chittick 1968). Low drystone walled enclosures (figure 10, plate 33) are found in several places round Aldabra (Voeltzkow 1897, p. 52), together with water-holes protected by rock slabs and blocks of imported rock far from the coast. All of these may be of some antiquity, but the enclosures have certainly been used and repaired in recent years, both to keep captured tortoises in before export, as at Anse Cedres, and to keep tortoises away from growing vegetables, as at Dune Jean-Louis. Because of the lack of water and distance from trade routes it is likely that pre-European visitors were castaways and not settlers: even the far more attractive Seychelles were apparently not settled in pre-European times (Sauer 1967).