Why did the mishna compare the case of two cups of blood to a sin offering that got lost and another was brought in its place? The gemara concludes that the msihna was brought in order to teach a case that can be derived from the mishna and not for the case itself. The mishna brings all sorts of cases where the laws of offering sacrifices outside do not apply either because of the type of offering (that isn’t offered inside the mikdash) or because of the animal brought (a disqualified animal). The mishna describes historically – when were sacrifices allowed to be brought outside the mishkan (bamot) and when were they forbidden? What were the laws regarding each time period (when they were allowed and when they weren’t)? What sacrifices were allowed to be brought anywhere (during the time when bamot were permitted)?