Eleven days from Chorev, by way of Har Se’ir to Kadesh-barnea.
Be’er Yosef: We understand Chorev to be none other than Har Sinai. After all, notes the gemara, this most important location went by five different names. Why call Sinai “Chorev?” Because, offers the same gemara, ruin/ churvah descended to the nations on Sinai. The gemara does not tell us what about the giving of the Torah was particularly ruinous to the rest of the world.
We can find clues if we look elsewhere to see what Chazal consider to be particularly devastating. One place that comes to mind is the conversation a barren Soro has with her husband Avrohom. She persuades him to take her servant Hagar as a consort, in the hope that “I will build from her,” meaning that Hagar will have a child, and Soro will act as a surrogate parent. Rashi, citing a midrash, draws the inference: If Soro will only “build” by having a child, then it follows that one who has not built, i.e. has not produced a child, lives in a state of destruction or ruin.
Now, the commandment to have children appears early in Chumash, well before matan Torah. The gemara states an unambiguous principle regarding mitzvos that appear in Chumash before Klal Yisrael received the Torah. If a mitzvah is given prior to Sinai and not repeated after the Torah was given to Klal Yisrael, then only Jews are responsible to uphold it. If it is repeated after matan Torah, then it devolves upon both Jews and non-Jews/ bnei Noach.
The Torah does not repeat the “be fruitful and multiply” mitzvah after Sinai. Therefore, obligation in this mitzvah shifts to Jews alone. Whereas before Sinai, all of mankind was commanded to propagate the species, this is no longer true after the Torah was given.
Another way of looking at this is that having children became optional for non-Jews after the giving of the Torah. This can only mean that Hashem was prepared for the possibility that a group of people might vanish in time because they could not replenish themselves across the generations. Because of Sinai, the “ruin” of other nations was introduced. They could now treat parenting as an option in which they might or might not be interested. HKBH no longer had a strong interest in maintaining their populations. The possibility of their ruin had descended upon them at Sinai.
This line of reasoning helps explain why Har Sinai is called “Chorev” in our pasuk. The Torah goes on to place the beginning of Devarim at a point in time just after the wars with Sichon and Og. Those battles ushered in a policy of destruction of the seven nations that occupied the Land at the time. This, too, was a reflection of the new reality that took hold after Sinai, in which Divine interest waned in sustaining the populations of other nations. Some would come and go. The most evil of them would disappear in the short run, as the Bnei Yisrael would replace them within the borders of Israel.
The Torah hints here at the source of their harsh treatment. Having been offered the Torah and spurning it, they had become expendable. Rejecting the Torah was tantamount to signing their own death warrants. Because of Sinai, their future was jeopardized. Their ruin had descended to them on that mountain, albeit by their own choosing.
 Based on Be’er Yosef, Devarim 1:2
 Shabbos 89B
 Bereishis 16:2
 Bereishis Rabbah 45:2