Tartessian is generally left unclassified for lack of data or proposed to be a language isolate for lack of connections to the Indo-European languages. Some Tartessian names have been interpreted as Indo-European, more specifically as Celtic. However, the language as a whole remains inexplicable from the Celtic or Indo-European point of view; the structure of Tartessian syllables appears to be incompatible with Celtic or even Indo-European phonetics and more compatible with Iberian or Basque; all Celtic elements are thought to be borrowings by some scholars.