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| | | | | | | | | P-Celtic languages | | | | | | | | | | Q-Celtic languages |
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| | | | | | Brythonic languages | | | | | | Gaulish | | Celtiberian | | | | | Goidelic |
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| Southwestern Brythonic language | | Pictish | | Old Welsh | | Cumbric | | | | | | | | | | | | Primitive Irish |
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| Cornish | | Breton | | Middle Welsh | | Lepontic | | Noric | | Galatian | | | Old Irish |
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| | | | | | | | Welsh | | | | | | | | | | | | | | | Middle Irish | | |
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| | | | | | | | | | | | | | | | | | | | | Manx | | Irish | | Scottish Gaelic |
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