[push] (back|) the frontiers

to expand the boundaries or limits of knowledge, discovery, or understanding, typically in science, technology, or exploration

Scientists continuously strive to push back the frontiers of medical research.
Explorers have always sought to push the frontiers of human knowledge by reaching uncharted territories.
The artistic avant-garde seeks to push the frontiers of conventional artistic expression.
The invention of the telescope helped astronomers push back the frontiers of our knowledge about the universe.
Last year, the exploration mission pushed the frontiers of space exploration by reaching new celestial bodies.

to extend the boundaries of a region or country, often through exploration, colonization, or territorial conquest

European explorers pushed back the frontiers of the known world by discovering new continents.
The westward expansion of the United States in the 19th century pushed the frontiers of the nation.
The Roman Empire's conquests in ancient times pushed back the frontiers of their dominion.
The Silk Road trade routes contributed to pushing the frontiers of cultural exchange between East and West.
Colonial powers pushed back the frontiers of their empires through overseas conquests.