I'm trying to understand the historical workings of Rosh Hodesh prior to Sanhedrin.
I assume that the entire concept of having possibly 2 days Rosh Hodesh was related to the timing of when witnesses appeared at Sanhedrin. Thus, the month could have been either 29 or 30 days long.
What happened before then? How was Rosh Hodesh declared? Didn't witnesses have to see the New Moon, then to, and who was in charge to declare Rosh Hodesh? And, even with all that, was there no doubt as to whether a month was 29 or 30 days long? In short, what factors caused this sense of doubt to make 2 days Rosh Hodesh that may not have been there , previously?