Over the past decade researchers trying to get to the bottom of UFO sightings have reported an overall increase world-wide. There are many contributing factors supporting this information aside from the distinct correlation that plainly there are more UFOs to be sighted. Consider the growth in the field for one instant, the shear number explosion of investigators, hobbyists, and those paying a little closer attention to the skies above. With a much larger array of trained spotters, it's common sense to say the number of sightings would elevate, at least to a notable point.
Agencies such as MUFON are finally gaining recognition for their accomplishments as more visitors seek to pour over the materials found in their database. Global phenomena like unidentified flying objects have swept the world by filling coherent reports by observers who have never communicated with each other. A similar phenomena exists in case reports studied by psychologists, of alien visitations, which uniformly describe the same experience from person to person although those people have never been in contact with each other. Of course, UFO sightings are a little different in the respect that the object can be witnessed by hundreds, if not thousands, at the same time. Lack of physical evidence and Earthly explanations often quickly dismiss claims especially when they're founded by individuals who appear discreditable or who have maintained states of panic while regurgitating their experience. A fabled fish has limitless size potential. The major mystery and clear turning point though is when stories remain consistent in every detail even with the most obscure points, while sharing a common ground with many other reports.
Shield sighting from Annales Laurissense
Mass sightings with complete coherent reports track back hundreds of years before the time of electronics and modern mass communication. One such example cites a flying disc shaped object traveling from Scotland, over Europe and into Asia. The sighting is well documented in woodcuts and gazettes from several towns who's only lines of communication were foot travel or by horse during the Dark Ages. In fact, dates on the news reports are close enough together that either gossip by foot or by horse would not have traveled fast enough. Also, many of the countries were at war. Why would any individual risk crossing into enemy territory to tell someone there about seeing a strange object in the sky?
The question doesn't end in the Dark Ages though several sightings during the period, in a heightened time of unrest and violence, do have similar descriptive terms. Fire in the sky burning and spinning. Revolving wheel or round barrel of flame. Long fiery beam, pile of fire the size of a small boat, dark object making a sound like a wheel, shaped like a drum and came from the sea. The execution of Nichiren, for example, was aborted as the executioner panicked and ran when he witnessed an object in the sky like a full moon suddenly appear. As well, the Japanese are first credited to the term "flying saucer" after a sighting in 1180CE describing a flying earthenware vessel leaving a luminous trail. As time traces further back, descriptions tend to remain similar in style but use different terms such as a flying globe of fire and circular shield in the sky. Even so far back into written history around 1450BCE where the annals of Thutmose III talking of circles of fire coming from the sky brighter than the brightness of the sun.
Of course one could easily attribute the more ancient UFO sightings to be nothing more than meteorites crashing to Earth, which do indeed fit the some descriptions. Celestial body movements and falling stars best explain a few of the accounts, but do not provide an accurate explanation for other events like the Nuremberg sky battle in which it's reported the objects were fighting with each other, so evident the onlookers could tell who was winning and who was losing. Another example is an account from Emperor Theodosius around 390CE describing a brilliant glowing orb in the sky with a great number of other glowing orbs drawing near the larger one, almost as if they were being pulled in. Theodosius claimed the spectacle to be like a swarm of bees flying around a bee-keeper until they blended together as one, becoming as bright to the eye as a double-edged sword. In fact, there are quite a few ancient UFO sightings that dismiss the comet or meteor theory altogether due to the irregular activity of the object, moving in such ways that a meteor is not capable of.
Source: Ancient Mysteries Blog