Why might vowel harmony in some Uralic languages reflect contact with Turkic languages?

The hypothesis that vowel harmony in Uralic languages reflects contact with Turkic languages is supported by an areal perspective rather than a strictly genetic one. While many scholars traditionally traced vowel harmony back to Proto-Uralic, this view is increasingly questioned in favor of an areal origin influenced by neighboring Turkic speakers.12

Several key factors support this interpretation:

• Geographic Proximity: With the exception of Baltic-Finnic, the Uralic languages that exhibit productive or active vowel harmony have historically had recent Turkic neighbors whose own languages utilized vowel harmony. For example, dialects of Mansi and Khanty that feature vowel harmony are located in close proximity to Tatar groups.1
• Eurasian Language Union: Uralic languages are situated within a broad "Eurasian language union," a concept proposed by Roman Jakobson. This region is characterized by features such as the contrast between palatalized and nonpalatalized consonants, which shares an acoustic basis with the front-back vowel contrast found in vowel harmony systems.1
• Absence in Distant Languages: Languages located far from Turkic influence, such as Sami, Estonian, and Livonian, lack vowel harmony, further suggesting that the feature is not a universal inheritance of the Uralic family but rather a result of regional contact.1