Breakdown of Этот этап продолжался с две тысячи четырнадцатого до две тысячи восемнадцатого года.
этот
this [f: эта, n: это]
два
two
год
year
тысяча
thousand
Questions & Answers about Этот этап продолжался с две тысячи четырнадцатого до две тысячи восемнадцатого года.
Why do we use words that look like 'fourteenth' and 'eighteenth' for the years?
In Russian, years are expressed using ordinal numbers (like 'the 2014th year'). Because we are using the prepositions с (from) and до (to/until), which both require the genitive case, the base forms четырнадцатый and восемнадцатый change to their genitive forms: четырнадцатого and восемнадцатого.
Why don't the words две and тысячи change to the genitive case as well?
When you decline compound ordinal numbers (like years) in Russian, only the very last word changes its case. Therefore, две тысячи stays in its base form, and only the final word of the number takes the genitive ending.
Why is the word года (year) only placed at the very end of the sentence?
It is standard in Russian to omit the first года to avoid repetition when expressing a span of time. While you could technically say с две тысячи четырнадцатого года, dropping it in the first half sounds much more natural, similar to how we say 'from 2014 to 2018' in English.
Why is the verb продолжался imperfective instead of perfective?
The verb продолжаться (to continue or to last) is imperfective here because it focuses on the continuous duration of the stage. Whenever you emphasize how long an action or state lasted, especially with a specific time span like с and до, you use the imperfective aspect.