The first link gives a brief description of Kurdish, which is part of the Indo-Iranian branch of the Indo-European language family, and was developed between 4,000 and 2,000 years ago (paragraph 1). The dialect of Kurmanji is spoken mainly in Turkey and the former Soviet states and written with either the Latin or Cyrillic alphabet depending on the location. Kurmanji claims the highest number of speakers. Sorani is the dialect of those who live in Iraq and Iran. This form is written with the Arabic script. Both dialects are recognized and promoted by the Kurdish Regional Government (KRG), the semi-autonomous political power in northern Iraq. There are other dialects spoken in more southern regions. Included are resources within the post for those who wish to learn Kurdish.
The next link gives a technical analysis of the phonetic differences in Kurdish dialects as well as comparing these to other Iranian languages. In trying to understand the history of the evolution of the Kurdish language, the authors use old Persian, middle Persian, Zazaki, and Gurani to make comparisons. The cultural identity of the Kurds is an important factor; There is great religious, ethnic, and linguistic diversity within those who identify as Kurdish. This adds complications when trying to determine whether Kurdish has many dialects or is actually a blending of many different languages. The conclusion is drawn that Kurdish is a relative of Balochi, however, there are fundamental differences.