Isaiah was a very important prophet, the prophecies written in the Book of Isaiah follow through from his day into eternity. He was the prophet that proclaimed that the 2520 curse was about to begin by giving us the starting periods of both the 2520s.
But why were there two 2520s and what happened to the Israelite nation?
Let's turn back to Genesis 29 and take a look at what I will refer to as prophecy shown to us through providence:
"And Laban had two daughters: the name of the elder was Leah, and the name of the younger was Rachel. Leah was tender eyed; but Rachel was beautiful and well favoured. And Jacob loved Rachel; and said, I will serve thee seven years for Rachel thy younger daughter. And Laban said, It is better that I give her to thee, than that I should give her to another man: abide with me. And Jacob served seven years for Rachel; and they seemed unto him but a few days, for the love he had to her. And Jacob said unto Laban, Give me my wife, for my days are fulfilled, that I may go in unto her. And Laban gathered together all the men of the place, and made a feast. And it came to pass in the evening, that he took Leah his daughter, and brought her to him; and he went in unto her. And Laban gave unto his daughter Leah Zilpah his maid for an handmaid. And it came to pass, that in the morning, behold, it was Leah: and he said to Laban, What is this thou hast done unto me? did not I serve with thee for Rachel? wherefore then hast thou beguiled me? And Laban said, It must not be so done in our country, to give the younger before the firstborn. Fulfil her week, and we will give thee this also for the service which thou shalt serve with me yet seven other years. And Jacob did so, and fulfilled her week: and he gave him Rachel his daughter to wife also. And Laban gave to Rachel his daughter Bilhah his handmaid to be her maid. And he went in also unto Rachel, and he loved also Rachel more than Leah, and served with him yet seven other years." Genesis 29:16-30
The circumstances that came to pass in Jacob's life are very similar to what happened to the Israelite nation. Ten children were born of Leah and the handmaids and two children were born of the chosen wife Rachel - ten Israelite tribes split from the two chosen tribes. Jacob served 2520 days or seven years for each of his wives - each division of Israel would serve a 2520 sentence.
What caused this split?
"And the LORD was angry with Solomon, because his heart was turned from the LORD God of Israel, which had appeared unto him twice, And had commanded him concerning this thing, that he should not go after other gods: but he kept not that which the LORD commanded. Wherefore the LORD said unto Solomon, Forasmuch as this is done of thee, and thou hast not kept my covenant and my statutes, which I have commanded thee, I will surely rend the kingdom from thee, and will give it to thy servant. Notwithstanding in thy days I will not do it for David thy father's sake: but I will rend it out of the hand of thy son. Howbeit I will not rend away all the kingdom; but will give one tribe to thy son for David my servant's sake, and for Jerusalem's sake which I have chosen." 1 Kings 11:9-13
God did raise up a mighty king to evangelize the world; the job that Solomon was originally raised up to do was taken out of the hands of Israel and given to a heathen idolatrous king to perform. After King Nebuchadnezzar was converted by his own 2520 experience, he brought the worship of the one true God to his world wide empire. Just think how great God would have made Solomon's kingdom if he had been faithful.
In accordance to the promise "Behold, a son shall be born to thee, who shall be a man of rest; and I will give him rest from all his enemies round about: for his name shall be Solomon, and I will give peace and quietness unto Israel in his days. He shall build an house for my name; and he shall be my son, and I will be his father; and I will establish the throne of his kingdom over Israel for ever." 1 Chronicles 22:9-10 the house David would rule Israel forever. This promise is also a prophecy of Jesus the Lion of the Tribe of Judah, the Son of God being born as a man through the descendants of David the king. It was this promise that kept the tribes of Judah and Benjamin, the southern tribes under the reign of Solomon's son Rehoboam.
"And I will take thee, and thou shalt reign according to all that thy soul desireth, and shalt be king over Israel. And it shall be, if thou wilt hearken unto all that I command thee, and wilt walk in my ways, and do that is right in my sight, to keep my statutes and my commandments, as David my servant did; that I will be with thee, and build thee a sure house, as I built for David, and will give Israel unto thee." 1 Kings 11:37-38
Finally, God through His prophet warns Jeroboam, just like He warned Israel, to hearken, walk in His ways, do right in His sight, keep His statutes and commandments and be blessed. This is the same statements that point to the 2520, the seven times curse and the blessings for obedience found in Leviticus 26 and Deuteronomy 28.
Below are the events that finalized the split of the twelve tribes that happened around 975 BC.
"That they sent and called him. And Jeroboam and all the congregation of Israel came, and spake unto Rehoboam, saying, Thy father made our yoke grievous: now therefore make thou the grievous service of thy father, and his heavy yoke which he put upon us, lighter, and we will serve thee. And he said unto them, Depart yet for three days, then come again to me. And the people departed. And king Rehoboam consulted with the old men, that stood before Solomon his father while he yet lived, and said, How do ye advise that I may answer this people? And they spake unto him, saying, If thou wilt be a servant unto this people this day, and wilt serve them, and answer them, and speak good words to them, then they will be thy servants for ever. But he forsook the counsel of the old men, which they had given him, and consulted with the young men that were grown up with him, and which stood before him: And he said unto them, What counsel give ye that we may answer this people, who have spoken to me, saying, Make the yoke which thy father did put upon us lighter? And the young men that were grown up with him spake unto him, saying, Thus shalt thou speak unto this people that spake unto thee, saying, Thy father made our yoke heavy, but make thou it lighter unto us; thus shalt thou say unto them, My little finger shall be thicker than my father's loins. And now whereas my father did lade you with a heavy yoke, I will add to your yoke: my father hath chastised you with whips, but I will chastise you with scorpions. So Jeroboam and all the people came to Rehoboam the third day, as the king had appointed, saying, Come to me again the third day. And the king answered the people roughly, and forsook the old men's counsel that they gave him; And spake to them after the counsel of the young men, saying, My father made your yoke heavy, and I will add to your yoke: my father also chastised you with whips, but I will chastise you with scorpions. Wherefore the king hearkened not unto the people; for the cause was from the LORD, that he might perform his saying, which the LORD spake by Ahijah the Shilonite unto Jeroboam the son of Nebat.
"So when all Israel saw that the king hearkened not unto them, the people answered the king, saying, What portion have we in David? neither have we inheritance in the son of Jesse: to your tents, O Israel: now see to thine own house, David. So Israel departed unto their tents. But as for the children of Israel which dwelt in the cities of Judah, Rehoboam reigned over them. Then king Rehoboam sent Adoram, who was over the tribute; and all Israel stoned him with stones, that he died. Therefore king Rehoboam made speed to get him up to his chariot, to flee to Jerusalem. So Israel rebelled against the house of David unto this day. And it came to pass, when all Israel heard that Jeroboam was come again, that they sent and called him unto the congregation, and made him king over all Israel: there was none that followed the house of David, but the tribe of Judah only. And when Rehoboam was come to Jerusalem, he assembled all the house of Judah, with the tribe of Benjamin, an hundred and fourscore thousand chosen men, which were warriors, to fight against the house of Israel, to bring the kingdom again to Rehoboam the son of Solomon. But the word of God came unto Shemaiah the man of God, saying, Speak unto Rehoboam, the son of Solomon, king of Judah, and unto all the house of Judah and Benjamin, and to the remnant of the people, saying, Thus saith the LORD, Ye shall not go up, nor fight against your brethren the children of Israel: return every man to his house; for this thing is from me. They hearkened therefore to the word of the LORD, and returned to depart, according to the word of the LORD." 1 Kings 12:3-24