Complex sentence: Historically, is older, and originally appeared in word-initial position as well; for Proto-Germanic (PGmc) and probably the earliest Old English it makes more sense to say that is an allophone of after a nasal or when geminated.
Split into simpler sentences: Historically, is older, and originally appeared in word-initial position as well. In Proto-Germanic (PGmc) and probably the earliest Old English it makes more sense to say that is an allophone of after a nasal or when geminated.