Cuneiform times of Parthian Empire (250 BC – AD 226). The last known cuneiform inscription, an astronomical text, was written in 75 AD. The complexity of the system prompted the development of a number of simplified versions of the script. Old Persian was written in a subset of simplified cuneiform characters known today as Old Persian cuneiform. It formed a semi-alphabetic syllabary, using far fewer wedge strokes than Assyrian used, together with a handful of logograms for frequently occurring words like "god" and "king". Ugaritic was written using the Ugaritic alphabet, a standard Semitic style alphabet (an "abjad") written using the
Elamite cuneiform to that of the Rosetta Stone's, were written in three different writing systems. The first was Old Persian, which was deciphered in 1802 by Georg Friedrich Grotefend. The second, Babylonian cuneiform, was deciphered shortly after the Old Persian text. Because Elamite is unlike its neighboring Semitic languages, the script's decipherment was delayed until the 1840s. Even today, lack of sources and comparative materials hinder further research of Elamite. Elamite radically reduced the number of cuneiform glyphs. From the entire history of the script, only 206 glyphs are used; at any one time, the number was fairly constant at about 130.