You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Iranian_languages

Context:
It was situated precisely in the western part of Central Asia that borders present-day Russia (and present-day Kazakhstan). It was in relative proximity to the other satem ethno-linguistic groups of the Indo-European family, like Thracian, Balto-Slavic and others, and to common Indo-European's original homeland (more precisely, the steppes of southern Russia to the north of the Caucasus), according to the reconstructed linguistic relationships of common Indo-European.

Question:
What language family did Thracian and Balto-Slavic belong to?

Indo-European