Comment by int_19h

And Phoenician and Proto-Sinaitic in turn derive from Egyptian hieroglyphs. Furthermore, most alphabets in the world derive from that same one source.

It goes to show just how powerful the idea of writing is - once you have a society where it's pervasive, all its neighbors acquire it from them in short order, and they usually do so by adapting the original writing script to their needs. I strongly suspect that the reason why alphabets (and to a lesser extent syllabaries) spread especially widely is because they are easier to adapt to a different language - usually, once you've learned a new alphabet, it's more or less readily obvious how to use it to approximate any language that you already know.

(Which is also how you get imperfect spellings even in brand new orthographies. Practicality usually beats purity.)