Carsten Niebuhr brought very complete and accurate copies of the inscriptions at Persepolis to Europe, published in 1767 in "Reisebeschreibungen nach Arabien" ("Account of travels to Arabia and other surrounding lands"). The set of characters that would later be known as Old Persian cuneiform, was soon perceived as being the simplest of the three types of cuneiform scripts that had been encountered, and because of this was understood as a prime candidate for decipherment (the two other, older and more complicated scripts were Elamite and Babylonian). Niebuhr identified that there were only 42 characters in the simpler category of inscriptions, which he named "Class I", and affirmed that this must therefore be an alphabetic script.