Was the defeat in the lowest land on earth?

The root d-n-w gives adnā two senses the lexicons carry side by side: nearest and lowest. The Sasanian campaign that broke the Byzantines ran through the Jordan rift toward Jerusalem — the Dead Sea basin, whose shore lies about 430 metres below sea level: the lowest exposed land on earth. That elevation was established by instrument — the barometric and triangulated surveys of the nineteenth century — twelve centuries after the text was fixed in writing. Classical exegesis read 'the nearest land of the Romans to Arabia'; the same region satisfies the second sense exactly. Both readings are on file, and the stamp covers the fit.

[18] Lynch, Narrative of the U.S. Expedition to the River Jordan and the Dead Sea (1849) · Lane, Arabic-English Lexicon, d-n-w · al-Ṭabarī, Jāmiʿ al-bayān ad 30:3