Here's Cosmas Indicopleustes' transcription of the surviving part of an inscription from Ptolemy III at Adulis on the Eritrean coast. This gets quoted by Bowersock in the
Throne of Adulis. It refers to capturing elephants from Ethiopia, as well the use of Indian elephants.
http://www.tertullian.org/fathers/cosmas_02_book2.htmThe great king, Ptolemy, son of King Ptolemy and Queen Arsinoe, twin gods, grandson of the two sovereigns King Ptolemy and Queen Berenice ---gods sôtêres----sprung from Hercules the son of Jupiter on the father's side, and on the mother's side from Dionysus the son of Jupiter----having received from his father the Kingdom of Egypt and Libya and Syria and Phoenicia and Cyprus, and Lycia and Caria, and the Islands of the Cyclades, made an expedition into Asia with forces of infantry and cavalry, and a fleet and elephants from the Troglodytes and Ethiopia----animals which his father and himself were the first to capture by hunting in those countries, and which they took down to Egypt, where they had them trained for employment in war. And when he had made himself master of all the country on this side of the Euphrates, and of Cilicia and Pamphylia and Ionia, and the Hellespont and Thrace, and of all the forces in the provinces, and of the Indian elephants, and had also made subject to his authority all the monarchs who ruled in these parts, he crossed the Euphrates river, and when he had subdued Mesopotamia and Babylonia and Susiana and Persis and Media, and all the rest of the country as far as Bactriana, and had collected all the spoils of the temples which had been taken away from Egypt by the Persians, he conveyed them to that country along with the other treasures, and sent back his troops by canals which had been dug....
From the same link here's a quote from the Periplus (first century AD).
95. 1 Conf. Periplus, c. 3. "To the south of the Moschophagi, near the sea, lies a small emporium about 4,000 stadia distant from Berenice, and called Ptolemais Theron, from which, in the days of the Ptolemies, the hunters whom they employed used to go up into the interior to catch elephants. This place was very suitable for the purpose, as it lay on the skirts of the great Nubian forest in which elephants abounded. Before it was made a depot for the elephant trade, the Egyptian Kings had to import these animals from Asia; but as the supply was precarious and the cost of their importation very great, Philadelphia made most tempting offers to the Ethiopian elephant hunters to induce them to abstain from eating the animal, or at least to reserve a portion of them for the royal stables. They rejected, however, all his offers, declaring that even for all Egypt they would not forego their favourite luxury."
According to Bowersock Ptolemais Theron ("Ptolemais of the Hunts") would have been on the Eritrean coast to the north of Adulis.
The emphasis on elephants in this text seems to reflect its placement in a part of East Africa where both elephant hunts and trade in ivory were common. That does not of course mean that Ptolemy and his father, or their surrogates, necessarily did their hunting in the immediate vicinity of Adulis. The reference to Troglodytis (more correctly Trogodytis) as well as Ethiopia indicates that the hunting went on across a very large territory well to the east of the Nile in East Africa. The territory of Trogodytis first appears in the fifth century BC in Herodotus, who called its inhabitants Trogolodytes, "cave dwellers", known for running fast, eating snakes, and squealing like bats. He located them vaguely in Ethiopia, but four centuries later the geographer Strabo placed them clearly between the Nile and the Red Sea, and it was in the intervening period between these two writers that Ptolemy III made his allusion to Trogodytis as a region for elephant hunting. The name of Ptolemais of the Hunts, which lay on the west coast of the Red Sea, presumably reflects the activity and roughly the chronological period to which Ptolemy refers. In the days of the Periplus, a little less than a century after Strabo, the elder Pliny wrote that the Trogodytes, "who live on the border of Ethiopia," made their living exclusively from hunting elephants.
A few documentary texts on papyrus provide tantalizing glimpses into the elephant industry of this period and the compensation paid to those who worked in it. Two are dated to the last years of the reign of Ptolemy III, and one explicitly mentions elephant ships at Berenice, including a ship that had sunk - presumably from its heavy load. An old canal was reopened linking the Nile an the Red Sea to facilitate contacts across the region, and conceivably this was the canal to which Ptolemy alludes in the enigmatic last words that survive from the inscription on the Adulis stele.