Arrival of Golden Age.........

"For the protection of the helpless and suffering humanity the Lord Himself will take some measure and He will manifest Himself as the Avataar. For the protection of the lowly and for ending the burden of the earth, the Lord will incarnate Himself. At the end of the Iron Age and by the very beginning of Satyuga/ Golden Age, the Lord will incarnate Himself for the protection of the lowly, And will perform wonderful sports and in this way the incarnated  will come destroy the enemies- according to sikhism'
There are several interpretations of what Avatars are and to what purpose they act. Avatar means "descent" and indicates a direct descent of Lord on earth There is a mention of 10 Avatars in Garuda Purana lists , with Kalki (Avatar) being the tenth. The Bhagavata Purana initially lists twenty-two avatars, but mentions an additional three leading to a  total of twenty-five avatars. Kalki is presented as the twenty-second avatar '
According to Kalki purana, an Avataar , who has power to change the course of time stream in the favour of the good. He will be one to whom the power to change the destiny of the world will be given.It states the evil family of the  Kalki  will spring from the back of Brahma(Brahmin an upper caste). They will descend to earth and cause mankind to turn towards depravity. When man stops offering yagna(Hindu Ritual) to the gods, Vishnu(Supreme power/god of universe) himself will descend to earth to rid the world of evil. He will be reborn as Kalki to noted Brahmin(Hindu caste) family in the city of Shambhala. As a young man, He will be mentored in the arts of war by Parashurama, the sixth incarnation of Vishnu. He will then set out across the world battling evil kings and false prophets. He finally defeats Kali/Demon and brings about the Satya yuga(Golden Age). Having completed His mission, He will assume his four-armed form and return to heaven as Vishnu.(Lord of Universe)

 

Arrival of Golden Age as per Puranas

 

The Agni Purana explains that when the evil men who pose as kings begin to feed on human beings and try to destroy the righteous, Kalki, as the son of Vishnuyasha, and Yajnavalkya as his priest and teacher, will destroy these evil men with His weapons. He will establish moral law in the form of the fourfold varnas, or the suitable organization of society in four classes. After that people will return to the path of righteousness. The Agni Purana also relates that Hari (god), after giving up the form of Kalki(Avatar), will go to heaven. Then the Satya Yuga(Golden Age) will return as before.

 

The Vishnu Purana also explains that, "When the practices taught in the Vedas and institutes of law have nearly ceased, and the close of the Demon age shall be nigh, a portion of that divine being who exists of His own spiritual nature, and who is the beginning and end, and who comprehends all things, shall descend upon earth. He will be born in the family of Vishnuyasha, an eminent brahmin of Shambhala village, as Kalki, endowed with eight superhuman faculties. By His irresistible might he will destroy all the barbarians and thieves, and all whose minds are devoted to iniquity. He will reestablish righteousness upon earth, and the minds of those who live at the end of the Kali age(Demon age) shall be awakened, and shall be as clear as crystal. The men who are thus changed by virtue of that peculiar time shall be as the seeds of human beings, and shall give birth to a race who will follow the laws of the Golden Age or Satya Yuga, the age of purity. As it is said, 'When the sun and moon, and the lunar asterism Tishya, and the planet Jupiter, are in one mansion, the Golden Age  shall return.'"

 

 The Padma Purana relates that Lord Kalki will end the age of Kali(demon)

 and will kill all the wicked barbarians and, thus, destroy the bad condition of the world. He will gather all of the distinguished brahmins(upper caste) and will propound the highest truth. He will know all the ways of life that have perished and will remove the prolonged hunger of the genuine brahmin(an upper caste) and the pious. He will be the only ruler of the world that cannot be controlled, and will be the banner of victory and adorable to the world.

The Bhagavata Purana states, "At the end of Demon Age, when there exist no topics on the subject of God, even at the residences of so-called saints and respectable gentlemen , and when the power of government is transferred to the hands of ministers elected from the evil men, and when nothing is known of the techniques of sacrifice, even by word, at that time the Lord will appear as the supreme chastiser.  It further describes Lord Kalki's(Avaatar's/lord of universe) activities as follows: "Lord Kalki, the Lord of the universe, will mount His swift white horse Devadatta and, sword in hand, travel over the earth exhibiting His eight mystic opulences and eight special qualities of Godhead. Displaying His unequaled effulgence and riding with great speed, He will kill by the millions those thieves who have dared dress as kings."