"Go extinct? "
"Get killed off? "
"Die of disease? "
"Get bred out of the population? "
"Get punished by God? "
"Go into hiding?"
Let's look at some Native legends from around the world -
In Peru, there is a legend of the giants reaching their shores long ago, devouring their men, raping their women, and then committing sodomy. "The natives say that our Lord God, unwilling to conceal so wicked a sin, sent them a punishment suited to the beastliness of the crime, and when all the giants were together engaged in this accursed practice THERE CAME A FEARFUL FIRE FROM HEAVEN TO THE ACCOMPANIMENT OF A GREAT NOISE, IN THE MIDST OF WHICH A SHINING ANGEL APPEARED HOLDING A SHARP, BRIGHT SWORD WITH WHICH HE SLEW THEM ALL AT A SINGLE STROKE, AND THE FIRE CONSUMED THEM LEAVING ONLY A FEW BONES AND SKULLS, WHICH GOD ALLOWED TO REMAIN UNCONSUMED AS A TOKEN OF THE PUNISHMENT."
In that case, above, they describe any number of angelic or real-world experiences, from a horrible storm to a volcanic eruption (Western US Natives mentioned that as a reason for many tribes making an exodus), meteorite strike, or other.
The Lenape had this account: Their people came from the west after a volcanic eruption drove them east. "The Lepane told, that they had found the further bank of the River of Fish (Mississippi) inhabited by a very powerful people, who dwelt in great villages, surrounded by high walls. They were very tall, so tall that the head of the tallest Lenape could not reach their arms, and their women were of higher stature and heavier limbs than the loftiest and largest man in the confederate nations. They were called the Allegewi, and were men delighting in red and black paint, and the shrill war-whoop, and the strife of the spear. Such was the relation and made by spies to their countrymen."
...They sent a message to the Allegewi to request permission to settle themselves in their neighborhood. This was refused them, but they obtained leave to pass through the country and seek a settlement farther to the eastward. They accordingly began to cross the Namesi Sipu, when the Allegewi, seeing that their numbers were so great, and in fact they consisted of many thousands, made a furious attack on those that had crossed, threatening them all with destruction, if they dared persist in coming over to their side of the river. Fired at the treachery of these people, and the great loss of men they had sustained, and besides, not being prepared for a conflict, the Lenape consulted on what was to be done; whether to retreat in the best manner they could, or try their strength, and let the enemy see they were not cowards. "Alleghans through force of arms."
"While one should always be aware that history as related by the victorious side may not be history as it actually occurred, never the less the resultant war is related as eventually becoming an overwhelming loss for the Alleghans. Whether the Lenape were considered deceitful in not disclosing their vast hoard is perhaps irrelevant. While ONE ACCOUNT SAYS THE ALLEGEWI WERE EXTIRPATED, ANOTHER RELATES OF THEIR ESCAPE DOWN THE MISSISSIPPI. The Lenni Lenape, having made an alliance with the Mengwe, took many years, and through a great loss of people, claim to have finally defeated the" Alleghans through force of arms."
"Stonish giants"
In "Ancient History of the Six Nations," David Cusick tells of the legend of the stonish giants - ("a tribe of the wilderness") came from the woods and attacked the tribes and war began. They were ravenous and devoured people. THEY WERE DRIVEN BACK INTO THE WILDERNESS.
Source: " Two miles from Mandan, on the bluffs near the junction of the Hart and Missouri Rivers (North Dakota), says the local newspaper, THE PIONEER, IS AN OLD CEMETERY OF FULLY 100 ACRES IN EXTENT FILLED WITH BONES OF A GIANT RACE. This vast city of the dead lies just east of the Fort Lincoln road. The ground has the appearance of having been filled with trenches piled full of dead bodies, both man and beast, and covered with several feet of earth. In many places mounds from 8 to 10 feet high, and some of them 100 feet or more in length, have been thrown up and are filled with bones, broken pottery, vases of various bright colored flint, and agates. The pottery is of a dark material beautifully decorated, delicate in finish, and as light as wood, showing the work of a people skilled in the arts and possessed of a high state of civilization. This has evidently been a grand battlefield, where thousands of men... have fallen. Nothing like a systematic or intelligent exploration has been made as only little holes two or three feet in depth have been dug in some of the mounds, but many parts of the anatomy of man and beast, and beautiful specimens of broken pottery and other curiosities, have been found in these feeble efforts at excavation. Five miles above Mandan, on the opposite side of the Missouri, is another vast cemetery as yet unexplored. We asked an aged Indian what his people knew of these ancient graveyards. He answered: "ME KNOW NOTHING ABOUT THEM. THEY WERE HERE BEFORE THE REDMAN."
The odd thing about these legends by Natives is that they are trying to explain something that happened, something outside of their understanding and so they attribute magical qualities to fill in the blanks in knowledge, kind of like when we experience ghostly interaction and tell a story of how surely it is the souls of the dead revisiting us. We don't understand the origin of the "phenomena," so we give it magical or other worldly origins. They also speak of these tall "white men" as being here when their people arrived to the continent, showing an earlier race of giants who had spread out across the world long before man on foot was overtaking the continents. In fact, early enough to mine, have civilizations and language. But, the land could only be held by one man, as these originators were a bloodthirsty and hungry group. It would appear the Native people of America (whose DNA did not match the Adena people) were, in fact, the true victors and the lands secured for their people.
In Australia, the aborigines had a legend of a giant who ate people and disrupted the community. Two women COAXED HIM INTO A CAVE WHERE THEY BURNED HIM. This is similar to the Paiutes' tale of trapping the man-eating giants in the cave in Nevada where THEY BURNED THEM WITH SAGE BRUSH FILLING THE OPENING OF THE CAVE. The Lenni-Lenape spoke of a race of giants they FOUGHT OFF BY JOINING FORCES WITH ANOTHER TRIBE, KILLING OFF MOST OF THE GIANTS AND SENDING THE REST DOWN THE MISSISSIPPI. The Cherokee speak of DRIVING OFF THE MOON-EYED PEOPLE who would only come out at night and feared the light. In these cases, it would appear that the masses rebelled, rather than God striking them down ("as in the Peruvian tale above").
"David Cusick, a Tuscorora [sic] by birth, writes in 1825 that among the legends of ancient stock, there was a powerful tribe called RONNONGWETOWANCA. They were giants, and had a "considerable habitation." He says that when the Great Spirit made the people, some of them became giants. The giants were said to have had a "silly" mode of attack, waiting until their intended victim was not expecting anything. After a time, and having endured the outrages of these giants, it is said that the people ended together, and through the final force of about 800 warriors, SUCCESSFULLY ANNIHILATED ALL OF THE ABHORRENT RONNONGWETOWANCA PEOPLE. After that, it was said that there were no giants anywhere. This was supposed to have happened around 2,500 winters before Columbus discovered America, i.e. around 1000 B.C.E.-the time that the Adena seem to have arrive in the Ohio Valley."
Bible: "The people of the ancient world accepted the presence of giants as a fact of history, and the Bible presents them as ENEMIES WHO WERE DESTROYED EITHER BY THE JUDGMENT OF GOD OR IN BATTLE WITH MEN."
In the case of David the shepherd in the Bible, HE SLEW GOLIATH THE GIANT WITH A STONE IN HIS SLINGSHOT.
Og of Bashan was a giant SLEWED BY MOSES AND HIS MEN.
In the story of the Iliad, the Trojans were assumed to be from another land, a different language than the Greeks, but understandable by association with perhaps some Indo-European dialect (interestingly Indo-Europeans had fair coloring, long narrow faces, long limbs) and were described as giants. These giants were brought down with what came to be called a "Trojan Horse" during the lengthy war with the Greeks. The giant horse was given as a gesture of capitulation to the giants who then partied and had fun to celebrate their winning the war, only to have the ENEMY SOLDIERS DESCENDING FROM THE HORSE AND ATTACKING THEM AT THEIR WEAKEST.
DEATH VALLEY
In descriptions of the giants of Death Valley supposedly found by a man in early 1900s in caves, the description of a giant hall of mummified giants was quite detailed and intriguing. The man described a chamber that looked like a meeting of all the warriors and they were mummified. HE ASSUMED THEY HAD TO HAVE DIED ALL TOGETHER SUDDENLY.
What we have to go on is a population of skeletons that were carefully buried in mounds and caves with their possessions, so there were tribes that cared for each member's eternal passage. But, what happened to those who served that purpose of burying others? Someone had to bury them or did they just retreat to a secret place to die along and their bones never be found? When did the last surviving giant pass? Or did they go to some hidden safe place?
CONCLUSION
It's intriguing to see that, even in the most ancient times, most remote locations, Native legend and religious texts, and mythology; all portray a giant culture that they had to deal with. This is not a coincidence or some make believe about dealing with strong foes. This is truth telling. There were giants and man around the world had to deal with this aggressive and powerful beings.
The question now becomes, what became of these giants? If it had been cataclysm, Homo sapiens would have been felled, as well.
It would seem there are two most likely scenarios; one is that the giants simply bred out of the population, unable to hybridize, perhaps difficulty with fertility and birthing, they simply went the way of Neanderthals, and the other possibility is that they still exist today in the descendants or people we refer to as Sasquatch.
The Paiutes had reported the red-haired giants as having the hair all over. This adds a new dimension to these tall beings from the past. The Northwest Natives, who elongated the skulls of tribe members, happened to have many legends of a hairy tall man.
We have a country in which we have many sightings of giants and also many bones of giants. We also have Native legends of killing giants and driving off the rest. Now, we have giants who rigidly work to avoid us short folks. We also have an interesting correlation between places bones were found and giants are seen today - hmmm....
MORE INFO:
All the Giants from the Bible
Death Valley Giants
Who were the trojans?
Ancient Giants in Warfare
Giants in mythology
Ancient War in America