The Book of Mormon is remarkably accurate in its descriptions of Arabia before Lehi and his family travel to the New World, but where would Joseph Smith have gotten his information?
Even if Joseph had access to the best available information of Arabia it would likely have been wrong.
Michael R. Ash explains:
In the case of ancient Arabia, we are amazed that Joseph Smith got so many things right when the literature of his day got so many things wrong. Virtually everything we know about ancient Arabia has come to light only since the Book of Mormon was published. As Hugh Nibley pointed out five decades ago in his book “Lehi in the Desert,” “The world through which Lehi wandered was to the westerner of 1830 a quaking bog without a visible inch of footing, lost in impenetrable fog; the best Bible students were hopelessly misinformed even about Palestine. Scientific study of the Holy Land began with Edward Robinson in 1838, yet 40 years later a leading authority writes: ‘Few countries are more traveled in than Palestine; and in few are the manners and customs of the people less known …’ “
the most complete general guide to Arabia that was likely available to Joseph described the whole southern coastline as a “rocky wall,” as “dismal and barren,” without so much as “a blade of grass or a green thing.” One book claimed that Arabia was so hot that animals were roasted on the plains and birds in midair.
Very few books mentioned any fertile regions in Arabia, and those that did got the information wrong as well — describing fertile regions as producing rice, maize and tropical fruits. The information in Smith’s day was so erroneous that even as late as the 1920s, explorers who visited Southern Arabia were surprised by the thickly wooded valleys. One article in a 1939 scholarly journal theorized that Solomon may have built ships from materials in the Mediterranean but wondered “where on the shores of the Red Sea could timber be found for shipbuilding?”– Michael R. Ash – Challenging Issues, Keeping the Faith: Book of Mormon gets Old World details right
How would Joseph know more than the experts of his day?