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:
Russian_language

Context:
Until the 20th century, the language's spoken form was the language of only the upper noble classes and urban population, as Russian peasants from the countryside continued to speak in their own dialects. By the mid-20th century, such dialects were forced out with the introduction of the compulsory education system that was established by the Soviet government. Despite the formalization of Standard Russian, some nonstandard dialectal features (such as fricative [ɣ] in Southern Russian dialects) are still observed in colloquial speech.

Question:
When did the Soviets establish required education?

the mid-20th century