Why is there no archaeological evidence of the Jews living in the desert for 40 years? James K. Hoffmeier, Ancient Israel in Sinai, pp. 150-153:
One might logically think that tents would leave little or no trace in the terrain of Sinai and Kadesh-Barnea, and we would not expect nomadic peoples who only occupy a particular spot for a short period of time to leave tangible evidence of their presence. In fact there has been a rather energetic debate about this matter in recent years. Of special interest to the current study is the question of whether nomads are discernible in the archaeological record. Finkelstein and Perevolotsky, who were engaged in considerable survey work in the Negev and Sinai, argue for only negligible evidence, if any, which is true not only of ancient desert dwellers but even of nineteenth-century Bedouin, whose traces are "difficult to identify." They further observe that "nomadic societies do not establish permanent houses, and the constant migration permits them to move only minimal belongings. Moreover, their limited resources do not facilitate the creation of a flourishing material culture that could leave rich archaeological finds." They acknowledge, however, that nomadic people do leave such evidence of their presence as cemeteries, desert kites (for hunting), cult places, and rock drawings. But for the most part, they speak of the "nomadic lifestyle" as "archaeologically 'invisible,'" one that does not leave an "archaeological footprint"...
Curiously, when it comes to the Israelites in Sinai, Finkelstein [in his book The Bible Unearthed] is adamant that "some archaeological traces of their generation-long wandering in the Sinai should be apparent"...
Although these considerations [to the contrary] must be borne in mind, I find Finkelstein's argument regarding the problem of detecting nomadic peoples in the archaeological record to be quite plausible and think it may explain why there is no clear evidence for the presence of the Israelites in Sinai. In a new monograph on tents in the Bible and the ancient Near East, Michael Homan came to the same conclusion as did Finkelstein and Perevolotsky, that "tents by their nature leave
very little for the archaeological record"...
Additionally, people traveling in the Near East used skins rather than pottery vessels to transport liquids. Pottery is heavy, and thus not very useful for people traveling in the desert...
The point of the foregoing discussion on tents and skin canteens is that such objects would not leave their mark on the archaeological record in Sinai or anywhere else. Stone and ceramic vessels would have been used on a limited basis by travelers like the Israelites. So it is not surprising that no clear archaeological evidence for the Israelites in Sinai has been found. To expect otherwise is unrealistic.