Sogdiana was an important nation on the Silk Road in Central Asia from around 400 BC to 1000 AD. Sogdian traders went far and wide as merchants, similar to the Phoenicians; like the Phoenicians, they spread their language and their script in disproportionate measure to their numbers.
The Sogdian script is variously described as being descended from Aramaic, Syriac, or Pahlavi. Like Pahlavi, it uses Aramaic logograms, but unlike Pahlavi, it did not press more consonants into vowel duty than Aramaic already did.
Unlike Aramaic, Sogdian used those double-duty consonants for both long and short vowels. Frequently, they would write an alef before the character when it was used as a short vowel instead of a long vowel — a handy disambiguation.
The fact that Sogdian usually wrote the short vowels means that it is verging on alphabetic. It isn’t really a classic alphabet because it doesn’t have unique glyphs for the vowels, but it isn’t really a classic abjad because it does have short vowels. Languages are messy and don’t fit into nice neat boxes!
Sogdian was around long enough that it developed three different sets of glyph shapes: Early Sogdian, Sutra script (around 500 AD), and what is somewhat confusingly called “Uyghar” script, not to be confused with the Old Uyghar alphabet (around 600 AD). The Early Sogdian script had disconnected letters. The next two were more cursive, i.e. connected, and also had different forms of the glyphs for the beginning, middle, and ending of words. As I mentioned in the Hebrew script posting, this is a clever way to enhance readability without using extra horizontal space.