Page "Balkan sprachbund" Paragraph 2

The earliest scholar to notice the similarities between Balkan languages belonging to different families was the Slovenian scholar Jernej Kopitar in 1829.

August Schleicher ( 1850 ) more explicitly developed the concept of areal relationships as opposed to genetic ones, and Franc Miklošič ( 1861 ) studied the relationships of Balkan Slavic and Romance more extensively.