In 1919, Edwin using the Hooker Telescope discovered that Andromeda and Triangulum were not nebulae and part of the Milky Way, but separate galaxies of their own, and since then other galaxies were discovered that were even further away than the Andromeda Galaxy, our nearest spiral galaxy.
Before Hubble's discovery, astronomers using the telescopes since Galileo and Kepler's time before Hubble, they all thought the Milky Way was the entire universe.
Below is image of small region in space, located in the Fornax constellation, known as Hubble Ultra-Deep Field (HUDF), from the Hubble Space Telescope.
It is not the whole universe, but only a tiny section of the universe, using the telescope full range, from ultraviolet to near-infrared lights. This image is the furthest image of the universe we can see, using an optical telescope. That's about 13 billion years ago, or when the universe was approximately 600 million years old.
(Source: Hubblesite (hubblesite.org), Hubble Ultra Deep Field 2014,
HubbleSite: Image - Hubble Ultra Deep Field 2014)
Like I said, it is not the whole universe, HUDF image showed only a small region in space, and that image displayed different 10,000 galaxies, not stars.