The Dragonflight is just the name for the mass migration of many species of dragon making their way from Northern Eduria to the southern lands to raise their young hatchlings in warmer climates. The exceptions are the ice and cave dragons of the Einlor Mountains and the lich dragons of Sylenndor.
Every year, in spring, the skies are often darkened by the Dragonflight. Most dragons are diurnal, but even so the migration does continue at night, albeit with less dragons.
Only the dragons know the routes. It is said that continent has pockets of magic dotted all over the lands, and the dragons use these to navigate. The Dragonriders of Wyrmgard, a city in the Einlor Mountains, are the only people who have been able to ride their dragons along the Dragonflight routes. For what reason, no one actually knows because the gates of Wyrmgard have been closed for several decades, and no one is allowed to enter.
The opposite of the Dragonflight is known as the Drakefall. The Drakefall is, like the Dragonflight, a migration of dragons - but these dragons are old, and are migrating to their lands of birth to die. Needless to say, the routes of the Drakefall are different from the Dragonflight, as many dragons don't like disturbing the old ones.
Elganis dragons don't participate in the Dragonflight and Drakefall because they are considered "transcended dragons" - a higher, far more intelligent race of dragons with an actual non-violent hierarchy and proper society. The Elganis are the only transcended dragons in Litvantar.
Syrellia is very used to the Dragonflight. Sometimes dragons stop to rest in the city. The inhabitants, regardless of district or faction, willingly help these exhausted dragons to get back on their feet.