There is ZERO trace of them. 2 million + people did not live in the desert for 40 years.
They followed the "Cloud" and only picked up and moved when the "Cloud" was taken up and moved. But when the "Cloud" stayed put, so did they. But when it moved, then the children of Israel followed it (the "Cloud") until it stopped again and it came down again and rested (stayed put) over the Tabernacle.
A "Cloud" by day and a resemblance of fire by night (in the sky). And it also fed them with "Manna" and prevented their clothing and shoes from wearing out for 40 years.
Book of Numbers
9:15 And on the day that the Tabernacle was reared up the "Cloud" covered the Tabernacle, [namely], the tent of The Covenant: and at even there was upon the Tabernacle as it were the resemblance of fire, until the morning.
9:16 So it was alway: the "Cloud" covered it [by day], and the resemblance of fire by night.
9:17 And when the "Cloud" was taken up from the Tabernacle, then after that the children of Israel journeyed: and in the place where the "Cloud" abode, there the children of Israel pitched their tents.
9:18 At the Commandment of the "I AM" the children of Israel journeyed, and at the Commandment of the "I AM" they pitched: as long as the "Cloud" abode upon the Tabernacle they rested in their tents.
9:19 And when the "Cloud" tarried long upon the Tabernacle many days, then the children of Israel kept the charge of the "I AM", and journeyed not.
9:20 And [so] it was, when the "Cloud" was a few days upon the Tabernacle; according to the Commandment of the "I AM" they abode in their tents, and according to the Commandment of the "I AM" they journeyed.
9:21 And [so] it was, when the "Cloud" abode from even unto the morning, and [that] the "Cloud" was taken up in the morning, then they journeyed: whether [it was] by day or by night that the "Cloud" was taken up, they journeyed.
9:22 Or [whether it were] two days, or a month, or a year, that the "Cloud" tarried upon the Tabernacle, remaining thereon, the children of Israel abode in their tents, and journeyed not: but when it was taken up, they journeyed.
9:23 At the Commandment of the "I AM" they rested in the tents, and at the Commandment of the "I AM" they journeyed: they kept the charge of the "I AM", at the Commandment of the "I AM" by the hand of Moses.
Book of Numbers
10:11 And it came to pass on the twentieth [day] of the second month, in the second year, that the "Cloud" was taken up from off the Tabernacle of The Covenant.
10:12 And the children of Israel took their journeys out of the wilderness of Sinai; and the "Cloud" rested in the wilderness of Paran.