Further discussion of incorporating towns together and then we learn about how the techum was actually measured

How do we determine a cities boundaries for the purpose of establishing a techum?

What happens if a person sets out to establish a eruv but turns back? What happens if a person leaves the techum but their 4 amot interlap with the techum?

what does the 2000 amah techum look like? and does one need food to set up an eruvei techumin or can it be done without food?

What happens if two people find themselves with no techum but overlapping 4 amot spaces? and what to do when Shabbat is approaching but a person is just under 4000 amot from home and one needs to be creative to get there

What happens if a person falls asleep without expressly stating their techum and a discussion about the exact parameters of one who is stuck with only four amot, ie. does not have a techum

A story when some Sages were on a boat approaching port as Shabbat drew close and what happens when a person legally leaves their techum on Shabbat.

A debate concerning the prayers of rosh hashanah, which, as the start of a month as well as the year is also rosh chodesh, and if they change based on the two day/one day debate. then we learn about what happens if a person finds themselves brought outside of their techum on shabbat

These mishnayot discuss setting up eruvin over the two days of Rosh Hashanah. Are they two separate days or one long period of holiness?

Making a conditional eruv and eruvin over two days