Syrian elephants are frequently mentioned in Hellenistic history; the Seleucid kings, who maintained numerous war elephants, reigned in Syria during that period. These elephants are believed to be Indian elephants ("E. m. indicus"), which had been acquired by the Seleucid kings during their eastern expansions; or they are believed to be a population of Indian elephants in the Middle East. It is attested by ancient sources such as Strabo and Polybius that Seleucid kings Seleucus I Nicator and Antiochus III the Great had large numbers of imported Indian elephants. Whether these "Indian elephants" were imported due to scarcity of native Syrian elephants, or due to their accomplished training and domestication as war elephants remains unclear.