Because all of my knowledge of Tifinagh came from the Wikipedia article, I was quite puzzled to read this.
For those of you that just don't bother checking, the author describes the different positions of English and French scholars.
Nobody is quite sure where the Berber script, used by the nomads of Northern Africa, came from. English sources are pretty certain that Tifinagh evolved from the Phoenician script that settlers brought with them when they founded Carthage in about 1000 BC. French sources admit the possibility that it evolved from a much older, unknown, native script. [...]
Both languages’ sources say that there was an eastern dialect and a western dialect of the script. Both agree that Tifinagh was used until about 200 AD, when the artifact record died out, but there is disagreement on the dating of the start of its use. Because of a small number of bilingual texts and its continuation into the modern era (more on that later), scholars are pretty sure what phonemes the glyphs correspond to. The English sources say that, like Etruscan, they cannot read the language. French sources say that the Eastern dialect has been deciphered. Because of who was in the area, they are both pretty sure it was a language of the Berber nomads. [...]
Unusually for scripts of that era, Tifinagh was usually written vertically, and even more unusually, most commonly from bottom-to-top. Only some glyphs were allowed at the beginning of lines. These could be used to tell which direction to read the writing in.
What evidence support either version? I am particularly interested about the French version, as I have some vague idea of the English one.