There is some scholarly debate over whether the 20 charts and mappae mundi in Piri's inscriptions includes the eight Ptolemaic maps, the four Portuguese maps, the Arabic map and the Columbus map. From one perspective, the number of charts and mappae mundi used by Piri equals 20, while in the other, it could mean a total of 34. Some have claimed that the source maps were found in the ancient Library of Alexandria, based on Piri's allusions to Alexander the Great, the founder of Alexandria, Ptolemy I, who ruled Alexandria in the 4th century BC, and Claudius Ptolemy, the Greek geographer and cartographer who lived in Alexandria during the 2nd century AD. Gregory McIntosh states "Arab writers often confused Claudius Ptolemy, the geographer of the second century C.E., with Ptolemy I, one of Alexander's generals... Piri Reis has undoubtedly made the same error, resulting in his believing the charts and maps were from the time of Ptolemy I instead of Claudius Ptolemy."