The hummingbird belongs to the order Apodiformes and the family Trochilidae. However, some zoologists classify them as a separate order, the Hummingbird Order, which includes around 113 genera and 366 species.

Modern hummingbirds are mainly found in Central and South America, with a few species inhabiting North America.

They occupy a wide range of habitats, from arid deserts to dense tropical rainforests and even the high plateaus of the Andes Mountains, ranging as far north as Alaska and as far south as the Tierra del Fuego archipelago.

In the 19th century, women in Europe and America commonly used hummingbird feathers as ornaments for hats, and there was also a market for hummingbird skins, posing a significant threat to their survival. In modern times, deforestation and agricultural development have gradually destroyed the habitats essential for hummingbird survival, putting some species at risk of extinction.

According to various studies, approximately 24-28 species of hummingbirds are classified as endangered or critically endangered, with many others experiencing population declines. In the past 150 years, species such as Brace's Emerald and the Middle American Emerald have become extinct.

The small size and fragile skeletons of hummingbirds make fossilization difficult, leaving much of their evolutionary history a mystery.

Most hummingbirds live in Central and South America, and fossils of hummingbirds dating back one million years have been found in South America, suggesting an origin in the Pleistocene epoch. However, scientists in southern Germany have discovered the oldest hummingbird fossils in the world, dating back over 30 million years to the Oligocene epoch, indicating that hummingbird ancestors appeared much earlier, likely during the Eocene epoch.

Studies suggest that the common ancestor of all modern hummingbirds lived in some regions of South America around 22.4 million years ago. This is a relatively recent origin for this modern bird family, especially considering that many extant species diversified rapidly after arriving in South America.

Because modern hummingbirds are found only in the Americas, how they migrated from Eurasia to South America remains a subject of debate among researchers. Considering their high energy needs, it is believed that they may have followed the Bering Land Bridge from Eurasia to North America before continuing their journey southward.

Once in South America, these nectar-feeding birds settled and diversified rapidly, utilizing a variety of habitats and resources, leading to the formation of nine main clades or groups, each containing hundreds of species. Approximately 120,000 years ago, these birds migrated back to North America, and around 5 million years ago, they invaded the Caribbean region multiple times.

Every organism in an ecosystem is constantly adapting to its environment and seeking the best means of survival. New species appear to be rapidly evolving and expanding within these biological zones (such as between North and South America).

However, over their 22.4 million years of evolution, the rate at which new hummingbird species appeared in the Andes Mountains was remarkably similar to the rate at which new species appeared in non-habitat regions, indicating the crucial role that mountainous areas played in the diversification of species. These findings are consistent with some studies on the impact of the Andes Mountains on biodiversity.