where does the name of the river comes from?
From the Proto-Indo-European root *"séles" ‘marsh’,
Saale
The name "Saale" comes from the Proto-Indo-European root *"séles" ‘marsh’, akin to Welsh "hêl, heledd" ‘river meadow’, Cornish "heyl" ‘estuary’, Greek "hélos" ‘marsh, meadow’, Sanskrit "sáras" ‘lake, pond’, "Sárasvati" ‘sacred river’, Old Persian "Harauvati" ‘Hārūt River; Arachosia’, Avestan "Haraxvatī", idem. It may also be related to the Indo-European root *"sal", "salt".

what is inner german border? It was a border between the German Democratic Republic (East Germany) and the Federal Republic of Germany (West Germany) from 1949 to 1990. was any escape method used here? Yes - by foot, hot-air balloon, swimming across the Baltic Sea does it have river border? Yes - the Elbe, the Werra and the Saale rivers where does the last river originate from? Großer Waldstein mountain near Zell
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Saale [SEP] Etymology
The name "Saale" comes from the Proto-Indo-European root *"séles" ‘marsh', akin to Welsh "hêl, heledd" ‘river meadow', Cornish "heyl" ‘estuary', Greek "hélos" ‘marsh, meadow', Sanskrit "sáras" ‘lake, pond', "Sárasvati" ‘sacred river', Old Persian "Harauvati" ‘Hārūt River; Arachosia', Avestan "Haraxvatī", idem. It may also be related to the Indo-European root *"sal", "salt". The Slavic name of the Saale, "Solawa", still found in Sorbian texts, comes from Old High German "sol", "salt", and "awa", "water".