In ancient times people had established the institution of hospitality. The institution of hospitality concerns the guest("stranger"in ancient times) and the host(host)and is known to us from the epics of Homer and specifically from the Odyssey. In many places in the Odyssey hospitality is described and each time the same ritual is followed, that is, the same rules are observed when the host is going to host someone.
We have a case of hospitality in Rhapsody D' of the Odyssey, in verses 23-347. There guests are Telemachus and Peisistratos and hosts are Menelaos and Eleni. The hospitality takes place in the house of the host, which is located in Sparta and specifically in the palace of King Menelaus. According to the etiquette of hospitality, when the foreigners arrived, menelaus' servants immediately arranged their horses and welcomed them to the palace. First they were put to bathe in the shiny baths and then they were put to sit on thrones next to the king. Immediately afterwards a healer holding a golden jup and poured water on them in a silver levetti to nibble their hands. Then he led them 
to a good-standing table where the cellar brought them a lot of edibles and the banker offered them tables with meats of all kinds and malamateni cups. Before they started eating, the king welcomed them and told them to eat and drink without even asking them who they were.
Also, the etiquette of hospitality is shown in rhapsody v,in verses 96-165. There, the noble goddess Calypso asks Hermes what is the reason why she brought him to her places and tells him that she is willing to 
do whatever he asks of her. She then takes him with her into her beautiful palace to kiss him. She sets the table where she offers him ambrosia and red nectar. Hermes, after eating and reliant, tells her what the reason for his trip is. After he finished with what he had to say, he left again for Olympus.The willingness with which they were welcomed without even asking them who they were and where they came from, shows how important and valuable the institution of hospitality had in Homeric society. It was created by the need of travelers to find a place to stay, since in those years people traveled for commercial reasons and there were no hotels. So people easily accepted strangers into their home to serve them but also to learn what is happening in other places.
In the Odyssey, however, at other points, some heroes express their fear of strangers.We have in Rhapsody III,in verses 63-74, such a case, where the host is Nestor and the guest is Telemachus. Nestor is afraid of foreigners because he believes that they may be 
pirates who wander around and bring danger and damage to the foreign world. Also in the same rhapsody in verses 150-152 and 226-228 speaks Odysseus, who is cautious, because he does not know which country he is in and is afraid that its inhabitants are wild and do not have the tradition of hospitality. Still, a little later in col. 243-245, Nausicaa tells her friends not to be afraid of the stranger they see, because the gods love the Phaeacians and protect them from enemies.
From the above we conclude that even in Homeric society, the unknown caused distrust and fear. The institution of hospitality, however, seems to have been imposed in the end for the protection of foreigners at a time when transportation was not 
easy nor was there a suitable infrastructure to stay, but also because it made it easier for peoples to communicate. The importance of this institution is also shown by its connection with religion, i.e. foreigners were protected by Zeus (Xenios Zeus). So it was everyone's moral obligation to offer hospitality.
Text written by students of our school.