The Milky Way to the Incas meant a Portal to the Otherworld.

The INCA EMPIRE controlled the largest territory in the history of the New World. Its dominion enclosed the lands from Chile to Ecuador, from the south to the north, and from the west to the east.
To the INCAS, the MILKY WAY was referred to as a RIVER flowing through the world of the stars.
The VILCANOTA River was its hologram running in its terrestrial land from the southeast to the northwest through the heart of PERU.
The VILCANOTA and the MILKY WAY were considered twins. Each are said to be the mirror images of one another as if they were entities connected somehow in different planes.
The INCAS believed that the orientation of the Milky Way run southeast to northwest; and during the twilight periods of the soltice, a CROSS was formed in the sky. This CROSS touched the four points on the horizon in which the sun rose and set during the equinoxes. This Cross divided the stars into FOUR separate directional quarters, forming the FOUR quarters of the territory that the Incas controlled, which they called "The Tawantinsuyu" which means "The land of the four quarters."
The INCAS believed that the souls of the deceased went to the "UPPER WORLD" which they called the "HURIN PACHA."
This world was visited by the living souls in the night while they were sleeping. They believed that dreams were the views of the eyes of the soul. It was possible because of the Milky Way which was the Portal to heaven from the ones who still were bound to a life in the earth.
The Portal had channels of energy in specific location in each quarter of the empire in which the priests took the offerings from the INCA and his people to the entities who were in charge of this type of communication to maintain the harmony in the empire and a clear connection with higher powers.
The timing of the INTI RAYMI celebration in the ritual calendar was an exact coordination with the time that the Milky Way aligned with the Vilcanota River. They believed that it was the time in which Heaven and Earth reconciled and the sun rose and set in the Milky Way, and the people came to celebrate this reconciliation, in other words Heaven and Earth came together in a complete harmony bringing order and peace in the whole universe.