To be “assumed” means to be taken up by God bodily into heaven. It happened to Enoch in the Old Testament (Gen. 5:24) and it also happened to Elijah (2 Kings 2:11 ). Some say Moses too was taken up since his grave is not known but the text is not clear as to that fact (cf Dt. 34:6).
Church Tradition and teaching going back as far as we can remember hold that Mary too, at her death was taken up, body and soul, into heaven. There is no earthly tomb containing her body, neither are there relics of her body to be found among the Christian faithful. She like Enoch and Elijah was taken up bodily to heaven.
It this recorded in Scripture? Yes and no. No the historical event of Mary’s assumption is not recorded. But the Bible does indicate her place in heaven. In Rev. 11 John records his sighting of the Ark of God!
Rev 11:19Then God’s temple in heaven was opened, and within his temple was seen the ark of his covenant. And there came flashes of lightning, rumblings, peals of thunder, an earthquake and a great hailstorm.
John then goes on to describe the Ark as he sees it and he describes the Ark as none other than Mary for this woman gives birth to a Son who is none other than Jesus:
A great and wondrous sign appeared in heaven: a woman clothed with the sun, with the moon under her feet and a crown of twelve stars on her head. 2She was pregnant and cried out in pain as she was about to give birth. 3Then another sign appeared in heaven: an enormous red dragon with seven heads and ten horns and seven crowns on his heads… The dragon stood in front of the woman who was about to give birth, so that he might devour her child the moment it was born. 5She gave birth to a son, a male child, who will rule all the nations with an iron scepter. (Rev 12:1-5)
The Woman is clearly Mary since the child is clearly Jesus. And where is Mary seen? In heaven. Hence Scripture confirms what is taught by the solemn Tradition of the Church that Mary, whose body is the Ark of the New Covenant is in heaven. Mary has been taken up to heaven.