Ancient Greek coins, such as the coins minted by Alexander's successor Lysimachus (360–281 BC), depict the ruler with the distinctive horns of Ammon on his head. Archaeologists have found a large number of different types of ancients coins depicting Alexander the Great with two horns. The 4th century BC silver "tetradrachmon" ("four "drachma"") coin, depicting a deified Alexander with two horns, replaced the 5th century BC Athenian silver "tetradrachmon" (which depicted the goddess Athena) as the most widely used coin in the Greek world. After Alexander's conquests, the "drachma" was used in many of the Hellenistic kingdoms in the Middle East, including the Ptolemaic kingdom in Alexandria. The Arabic unit of currency known as the "dirham", known from pre-Islamic times up to the present day, inherited its name from the "drachma". In the late 2nd century BC, silver coins depicting Alexander with ram horns were used as a principal coinage in Arabia and were issued by an Arab ruler by the name of Abi'el who ruled in the south-eastern region of the Arabian Peninsula.