According to the bible (2. book Moses (Exodus), chapter 25) the Hebrews created three outstanding relics during the exodus. The ark of the covenant, the bread display table and the seven arm candlestick called Menora. Being portable, of extreme symbolic value and even considerable material value these items have stimulated to fantasies of treasure hunters and explorers from the beginning.
Of course much esoteric nonsense has been written on these items. In particular the alleged harmful properties of the ark of the covenant caused many speculations. Unfortunately, this often causes serious scientists to avoid this topic. In consequence, we do not as much as possible about it. Regrettably, this is true for many interesting history riddles. In the case of these three biblical treasures, though, I am sure that these items at least once existed because two of them, the table and the Menora, are mentioned in several later, non-biblical sources. More on this in the following chapters that deal with both objects.
From Exodus chapter 25 we have a rather precise description of its outward appearance. A portable box made of gold plated acacia wood. Four golden rings hold gold plated acacia wooden beams to carry it. It was used to carry the stone tablets with the ten commandments.
The ark of the covenant is the most mysterious of the three items. It is the first to disappear into the mist of time. From a certain point of time it is just not mentioned any more, neither in the bible nor anywhere else. No account whatsoever of its fate is given. This point in time is approximately. the 7. century BC. Everything else is left to speculation.
It is possible that the ark was taken by the Babylonian army when they conquered Jerusalem in 587 BC. (The Hebraic history contains several attempts to raise against a vastly superior enemy, usually resulting in a disaster. This happened two more times against the Romans in 66-70 AD and 133-135 AD). However, there are no Babylonian accounts on any captured ark. The bible lists some taken items but does not mention the Ark. (2. Book of Kings chapter 25).
As far as I know the Babylonians handed back the captured religious treasures when they allowed the Hebrews 40 years later to return home.
An Ethiopian legend claims that a son of King David stole the ark and brought it to Ethiopia. The country has many churches keeping replicas of Jewish religious objects. It is said that the church of Aksum contains the ark. Nobody is allowed to see it. Once a year the alleged ark, hidden in cloth, is carried through the streets of Aksum. In my opinion this is just a pious legend. If they had the real ark they would show it at least occasionally to impress the believers. After all, it is the main purpose of religious relics to impress and attract believers. A secret relic is a contradiction.
I think the Ethiopian church knows they do not have the real thing so they do not allow any examination, not even a visual examination. In the late 19. century a single European saw it. It was a French priest named Dimotheos or Dimotheus. He described it as a stone plate 24x22x3cm of size. Apparently the 10 commandments were inscribed. He did not recognise the language but it certainly was not old Hebrew. He was sure it was a Christian creation dating to the 14. century or younger. Mr. Dimotheos wrote a small book from which today just a few copies exist. (R.P.Dimotheus, Deux Ans de Séjour en Abyssinie ou Vie Morale, Politique et Religieuse des Abyssiniens. Jerusalem 1871.)
Another story is provided in the Book of Maccabees. It states the Ark was hidden by prophet Jeremia at Mount Nebo before the Babylonians conquered the temple. According to the bible Mt. Nebo is also the last resting place of Moses. However, the Book of Maccabees is a relative young source and considered a visionary text without historical value.
In my opinion the fact base is insufficient for a serious search.