CMB was released 380'000 years after the Big Bang. Until then the universe was dark and opaque. This was followed by a long epoch when the universe became transparent but still dark because no stars were formed yet.
Stars and galaxies started forming about 200~300 million years after the Big Bang & these young stars started producing light into the infant universe. But their photons were only locally visible; because this light was absorbed by the surrounding neutral hydrogen.
Over time, this UV radiation ionized neutral hydrogen & gradually from 500 million to one billion years after the Big Bang, star light was eventually able to travel across the universe freely.
Stars and galaxies started forming about 200~300 million years after the Big Bang & these young stars started producing light into the infant universe. But their photons were only locally visible; because this light was absorbed by the surrounding neutral hydrogen.
Over time, this UV radiation ionized neutral hydrogen & gradually from 500 million to one billion years after the Big Bang, star light was eventually able to travel across the universe freely.
