Berakhot 162

1:
This mishnah sounds to our ears rather strange. Why should one pray when entering and leaving a city? In order to understand we must be aware of the background. In Eretz-Israel under Roman rule each municipality was run independently, on the model of the Greek city-states. In some cities the inhabitants were able to establish a worthy system of maintaining law and order: police, courts, judges, bailiffs and so forth. In other cities, even if these institutions existed, they were next to useless if they could not impose themselves on the criminal elements. A third problem was, of course, those cities where these institutions existed and wielded effective power, but were hopelessly corrupt.

2:
We must also recall that during the period of Roman and Byzantine rule in Eretz-Israel (approximately 60 BCE to 600 CE) the status Jews gradually changed as the population changed. At the beginning of Roman rule Eretz-Israel was predominantly Jewish; before the fall of the Western Empire (450 CE approximately) the population was very mixed; by the end of Byzantine rule the Jews were a decided minority in Eretz-Israel. A Jew entering a city that was administered by non-Jews (and where there was possibly no Jewish presence) could not know whether there was law, order and justice in the city, law and order but no justice, or near anarchy. This is why it was but natural that a Jewish traveler would pray "upon entering and … upon leaving" a city.

3:
The Gemara [Berakhot 60a] quotes the prayers as follows:

4:
The language of the above-quoted baraita would suggest that the greatest danger was at the city gates. This was were taxes were leveled and so forth: any unprotected traveller could be sure that if he and his belongings were in danger it would be at the gates that they were in the greatest danger of corrupt confiscation or simple robbery.

5:
The language of the baraita also shows us that the opinion of Ben-Azzai as quoted in the mishnah, is the accepted halakhah. For we can see here four prayers: before entering there is a plea for the future and after entering an expression of gratitude; upon exiting there is also a plea for the future and after exiting both an expression of gratitude and a plea for the future. Reading between the lines of these prayers we can perceive the dangers of traveling the roads of Eretz-Israel during the first centuries of this era.

6:
By the time we reach the period of the Amoraim in Babylon we can see a change. Rav Mattana limits our mishnah to a metropolis in which the courts do not sit and there is no death penalty; "but where there is a court to sit and where there is the death penalty we pay no attention to this [mishnah]".

To be continued.