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:
Estonian_language

Context:
The two different historical Estonian languages (sometimes considered dialects), the North and South Estonian languages, are based on the ancestors of modern Estonians' migration into the territory of Estonia in at least two different waves, both groups speaking considerably different Finnic vernaculars. Modern standard Estonian has evolved on the basis of the dialects of Northern Estonia.

Question:
What was the minimum number of waves through which modern Estonians migrated into Estonia?

two