Then your south quarter shall be from the wilderness of Zin along by the coast of Edom, and your south border shall be the outmost coast of the salt sea eastward:

Wesley's Notes

34:3 Your fourth quarter - Which is here described from east to west by divers windings and turnings, by reason of the mountains and rivers. The salt sea - So called from the salt and sulphurous taste of its waters. Eastward - That is, at the eastern part of that sea, where the eastern and southern borders meet.

Jamieson-Fausset-Brown Bible Commentary

3-5. your south quarter-The line which bounded it on the south is the most difficult to trace. According to the best biblical geographers, the leading points here defined are as follows: The southwest angle of the southern boundary should be where the wilderness of Zin touches the border of Edom, so that the southern boundary should extend eastward from the extremity of the Dead Sea, wind around the precipitous ridge of Akrabbim ("scorpions"), thought to be the high and difficult Pass of Safeh, which crosses the stream that flows from the south into the Jordan-that is, the great valley of the Arabah, reaching from the Dead to the Red Sea.

Matthew Henry's Concise Commentary

34:1-15 Canaan was of small extent; as it is here bounded, it is but about 160 miles in length, and about 50 in breadth; yet this was the country promised to the father of the faithful, and the possession of the seed of Israel. This was that little spot of ground, in which alone, for many ages, God was known. This was the vineyard of the Lord, the garden enclosed; but as it is with gardens and vineyards, the narrowness of the space was made up by the fruitfulness of the soil. Though the earth is the Lord's, and the fulness thereof, yet few know him, and serve him; but those few are happy, because fruitful to God. Also, see how little a share of the world God gives to his own people. Those who have their portion in heaven, have reason to be content with a small pittance of this earth. Yet a little that a righteous man has, having it from the love of God, and with his blessing, is far better and more comfortable than the riches of many wicked.

Matthew Henry's Whole Bible Commentary

Chapter 34

In this chapter God directs Moses, and he is to direct Israel, I. Concerning the bounds and borders of the land of Canaan (v. 1-15). II. Concerning the division and distribution of it to the tribes of Israel (v. 16, etc.).

Verses 1-15

We have here a particular draught of the line by which the land of Canaan was meted, and bounded, on all sides. God directs Moses to settle it here, not as a geographer in his map, merely to please the curious, but as a prince in his grant, that it may be certainly known what passes, and is conveyed, by the grant. There was a much larger possession promised them, which in due time they would have possessed if they had been obedient, reaching even to the river Euphrates, Deu. 11:24. And even so far the dominion of Israel did extend in David's time and Solomon's, 2 Chr. 9:26. But this which is here described is Canaan only, which was the lot of the nine tribes and a half, for the other two and a half were already settled, v. 14, 15. Now concerning the limits of Canaan observe,

I. That it was limited within certain bounds: for God appoints the bounds of our habitation, Acts 17:26. The borders are set them, 1. That they might know whom they were to dispossess, and how far the commission which was given them extended (ch. 33:53), that they should drive out the inhabitants. Those that lay within these borders, and those only, they must destroy; hitherto their bloody sword must go, and no further. 2. That they might know what to expect the possession of themselves. God would not have his people to enlarge their desire of worldly possessions, but to know when they have enough, and to rest satisfied with it. The Israelites themselves must not be placed alone in the midst of the earth, but must leave room for their neighbours to live by them. God sets bounds to our lot; let us then set bounds to our desires, and bring our mind to our condition.

II. That it lay comparatively in a very little compass: as it is here bounded, it is reckoned to be but about 160 miles in length and about fifty in breadth; perhaps it did not contain more than half as much ground as England, and yet this is the country which was promised to the father of the faithful and was the possession of the seed of Israel. This was that little spot of ground in which only, for many ages, God was known, and his name was great, Ps. 76:1. This was the vineyard of the Lord, the garden enclosed; but, as it is with gardens and vineyards, the narrowness of the extent was abundantly compensated by the extraordinary fruitfulness of the soil, otherwise it could not have subsisted so numerous a nation as did inhabit it. See here then, 1. How small a part of the world God has for himself. Though the earth is his, and the fullness thereof, yet few have the knowledge of him and serve him; but those few are happy, very happy, because fruitful to God. 2. How small a share of the world God often gives to his own people. Those that have their portion in heaven have reason to be content with a small pittance of this earth; but, as here, what is wanting in quantity is made up in quality; a little that a righteous man has, having it from the love of God and with his blessing, is far better and more comfortable than the riches of many wicked, Ps. 37:16.

III. It is observable what the bounds and limits of it were. 1. Canaan was itself a pleasant land (so it is called Dan. 8:9), and yet it bordered upon wilderness and seas, and was surrounded with divers melancholy prospects. Thus the vineyard of the church is compassed on all hands with the desert of this world, which serves as a foil to it, to make it appear the more beautiful for situation. 2. Many of its borders were its defences and natural fortifications, to render the access of enemies the more difficult, and to intimate to Israel that the God of nature was their protector, and with his favour would compass them as with a shield. 3. The border reached to the river of Egypt (v. 5), that the sight of that country which they could look into out of their own might remind them of their bondage there, and their wonderful deliverance thence. 4. Their border is here made to begin at the Salt Sea (v. 3), and there it ends, v. 12. This was the remaining lasting monument of the destruction of Sodom and Gomorrah. That pleasant fruitful vale in which these cities stood became a lake, which was never stirred by any wind, bore no vessels, was replenished with no fish, no living creature of any sort being found in it, therefore called the Dead Sea. This was part of their border, that it might be a constant warning to them to take heed of those sins which had been the ruin of Sodom; yet the iniquity of Sodom was afterwards found in Israel (Eze. 16:49), for which Canaan was made, though not a salt sea as Sodom, yet a barren soil, and continues so to this day. 5. Their western border was the Great Sea (v. 6), which is now called the Mediterranean. Some consider this sea itself to have been a part of their possession, and that by virtue of this grant, they had the dominion of it, and, if they had not forfeited it by sin, might have rode masters of it.