Yevamot is the first tractate in the order of Nashim. Admittedly, some commentaries place Yevamot after Gittin (Meiri), but this is not widely accepted. While the tractate focuses mainly on the halakhot of levirate marriage, the elucidation of these halakhot necessitates an in-depth clarification of the halakhot of marriage in general. Consequently, the comprehensive discussions of tractate Yevamot form the basis of the entire order of Nashim. 

Begins with Perek 8, Daf 70A