The Histories · 7.126

Now there are in these parts both many lions and also wild oxen, those that have the very large horns which are often brought into Hellas: and the limit within which these lions are found is on the one side the river Nestos, which flows through Abdera, and on the other the Achelos, which flows through Acarnania; for neither do the East of the Nestos, in any part of Europe before you come to this, would you see a lion, nor again in the remaining part of the continent to the West of the Acheloos, but they are produced in the middle space between these rivers.

Herodotus of Halicarnassus · trans. G. C. Macaulay, 1890
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