Oil on Board.
The Ruby-throated humming bird makes epic journeys on its migration - spending summers in North America and winters in Mexico or Central America - often returning to the same area year after year, although little is known of their routes. They presumably fly overhead of humans making a similar journey in search of work from Central America to North America.
Some of the humans making this journey could have ancestors who created artefacts of knotted string. Often these creations are intricate and obviously carry some meaning but that meaning has since been lost.