THE PROMISED LAND
Key Ref: Wickipedia

The promise was first made to Abraham (Genesis 15:18-21 ), then confirmed to his son Isaac (Genesis 26:3), and then to Isaac's son Jacob (Genesis 28:13 ), Abraham's grandson. The promised land was described in terms of the territory from the River of Egypt to the Euphrates river (Exodus 23:31). A smaller area of former Canaanite land and land east of the Jordan River was conquered and occupied by their descendants, the Israelites, after Moses led the Exodus out of Egypt (Numbers 34:1-12 ), and this occupation was  interpreted as God's fulfilment of the promise (Deuteronomy 1:8 ). Moses anticipated that God might subsequently give the Israelites land reflecting the boundaries of God's original promise, if they were obedient to the covenant (Deuteronomy 19:8-9).

[Genesis 12:1]:
The LORD had said to Abram, "Leave your country, your people and your father's household and go to the land I will show you."

[Genesis 12:7]:
The LORD appeared to Abram and said, "To your offspring [or seed] I will give this land."

[Gen 15:18-21]:
"On that day the LORD made a covenant with Abram and said, 'To your descendants I give
this land, from the river of Egypt to the great river, the Euphrates - the land of the Kenites, Kenizzites, Kadmonites, Hittites, Perizzites, Rephaim, Amorites, Canaanites, Girgashites and Jebusites."

The promise was confirmed to Jacob at Genesis 28:13, though the borders are still vague and is in terms of "the land on which you are lying".

[Gen 28:13]:
"And behold, the LORD stood above it and said, [to Jacob] 'I am the LORD, the God of your father Abraham and the God of Isaac; the land on which you lie, I will give it to you and to your descendants.' "

[Ex 23:31]:
"I will fix your boundary from the Red Sea to the sea of the Philistines, and from the wilderness to the River Euphrates; for I will deliver the inhabitants of the land into your hand, and you will drive them out before you."

Other geographical borders are given in Exodus 23:31 which describes borders as marked by the Red Sea, the "Sea of the Philistines" i.e. the Mediterranean, and the "River," (the Euphrates).

The promise is fulfilled at the end of the Exodus from Egypt:

[Dt 1:8]:
" 'See, I have placed the land before you; go in and possess the land which the LORD swore to give to your fathers, to Abraham, to Isaac, and to Jacob, to them and their descendants after them.' "

It took a long time before the Israelites could subdue the Canaanite inhabitants of the land.
The furthest extent of the Land of Israel was achieved during the time of the united Kingdom of Israel under David. The actual land controlled by the Israelites has fluctuated considerably over time, and at times the land has been under the control of various empires.

Numbers 34:1-12 (NASB)
1  Then the LORD spoke to Moses, saying,
2  "Command the sons of Israel and say to them, 'When you enter the land of Canaan, this is the land that shall fall to you as an inheritance, even the land of Canaan according to its borders.
3  'Your southern sector shall extend from the wilderness of Zin along the side of Edom, and your southern border shall extend from the end of the Salt Sea eastward.
4  'Then your border shall turn direction from the south to the ascent of Akrabbim and continue to Zin, and its termination shall be to the south of Kadesh-barnea; and it shall reach Hazaraddar and continue to Azmon.
5  'The border shall turn direction from Azmon to the brook of Egypt, and its termination shall be at the sea.
6  'As for the western border, you shall have the Great Sea, that is, its coastline; this shall be your west border.
7  'And this shall be your north border: you shall draw your border line from the Great Sea to Mount Hor.
8  'You shall draw a line from Mount Hor to the Lebo-hamath, and the termination of the border shall be at Zedad;
9  and the border shall proceed to Ziphron, and its termination shall be at Hazar-enan. This shall be your north border.
10  'For your eastern border you shall also draw a line from Hazar-enan to Shepham,
11  and the border shall go down from Shepham to Riblah on the east side of Ain; and the border shall go down and reach to the slope on the east side of the Sea of Chinnereth.
12  'And the border shall go down to the Jordan and its termination shall be at the Salt Sea. This shall be your land according to its borders all around.' "

Boundaries of the 'Promised Land' given by c.400
You may delineate the Promised Land of Moses from the Book of Numbers (ch. 34): as bounded on the south by the desert tract called Sina, between the Dead Sea and the city of Kadesh-barnea, [which is located with the Arabah to the east] and continues to the west, as far as the river of Egypt, that discharges into the open sea near the city of Rhinocolara; as bounded on the west by the sea along the coasts of Palestine, Phoenicia, Coele‑Syria, and Cilicia; as bounded on the north by the circle formed by the Taurus Mountains and Zephyrium and extending to Hamath, called Epiphany‑Syria; as bounded on the east by the city of Antioch Hippos and Lake Kinneret, now called Tiberias, and then the Jordan River which discharges into the salt sea, now called the Dead Sea.

1845: Salomon Munk, Palestine, Description Géographique, Historique et Archéologique," in
"L'Univers Pittoresque:

"Under the name Palestine, we comprehend the small country formerly inhabited by the Israelites, and which is today part of Acre and Damascus *pachalics. It stretched between 31 and 33° N. latitude and between 32 and 35° degrees E. longitude, an area of about 1300 French: lieues carrées."
*jurisdictions of a pasha - of an appointed ruler