How might sharing a body of water impact on the way countries get along and depend upon each other?

it depends it could be well or it could cause a war

Explanation:

why it might not work:

1. they might fight for the same resources

2. if there is  not enough food people might need to get it from other countries and end up in a war

3. if there was a war going you would have to join and help

4. people might make wrong accusations

why its good:

1. if a country is on the verge of war they could negotiate

2. if there are  allies  then they could share food

3. trading

4. they can help each other grow

european feudalism was a combination of legal and military customs in medieval europe that flourished between the 9th and 15th centuries. broadly defined, it was a way of structuring society around relationships derived from the holding of land in exchange for service or labour.

japanese feudalism. the era of feudalism in japan took place from the 12th through 19th centuries. during that period local rulers, either powerful families or military warlords, dominated the land, while the emperor was merely a figurehead and not a significant political presence.