It is written, that the Book of Daniel held information that is vital for the Christians in the last days to understand:
Matthew 24:15 When ye therefore shall see the abomination of desolation, spoken of by Daniel the prophet, stand in the holy place, (whoso readeth, let him understand:)
Mark 13:14 But when ye shall see the abomination of desolation, spoken of by Daniel the prophet, standing where it ought not, (let him that readeth understand,) then let them that be in Judaea flee to the mountains:
There were numberings of days/years in the prophecies that had not yet been fully understood:
Daniel 8:26 And the vision of the evening and the morning which was told is true: wherefore shut thou up the vision; for it shall be for many days.
Daniel 8:27 And I Daniel fainted, and was sick certain days; afterward I rose up, and did the king's business; and I was astonished at the vision, but none understood it.
While Daniel and many had some understanding of the previous vision (Daniel 7:1, 8:1), and of much of Daniel 8, being explained by Gabriel (Daniel 8:20-25), one major part of the longest time prophecy in the Bible was not understood:
Daniel 8:13 Then I heard one saint speaking, and another saint said unto that certain saint which spake, How long shall be the vision concerning the daily sacrifice, and the transgression of desolation, to give both the sanctuary and the host to be trodden under foot?
Daniel 8:14 And he said unto me, Unto two thousand and three hundred days (Heb. lit.: evening mornings); then shall the sanctuary be cleansed.
We know that the beginning of the counting of this prophecy began in the first of the vision, with th eRam (Medo-Persia; Daniel 8:20) and continued through the first king of the He-goat (Daniel 8:21) and through the time frame of the division of Greece (He-goat; Daniel 7:6, 8:22; 11:4-19), even unto the kingdom which followed it that conquered the promised land (Daniel 8:9,23; Deuteronomy 28:48-57, that nation of "iron" (Daniel 2:33,40, 7:7,19, whose symbol was the "eagle" (Matthew 24:28; Luke 17:37), that beseiged Jerusalem), and beyond into its own division, and far down to our close timeframe.
Many time prophecies would sub-divided it:
70 Weeks (and its sub-divisions, 7, 62, 1 (and its sub-divison, 3 1/2 and 3 1/2, ending in AD 34), the beginning of the 2,300, as per Daniel 9:24-27; Ezr 6:14, 7:1-28).
1260 days/years as per Daniel 7:25, 12:7; Revelation 11:2-3, 12:6,14, 13:5; Luke 21:24 (Revelation 11:2-3)
1290 days/years as per Daniel 12:11
1335 days/years as per Daniel 12:12-13; Revelation 14:13
10 days/years as per Revelation 2:10
3 1/2 days/years as per Revelation 11:9,11
All of which are part of the greatest, 2,300 of Daniel 8:13-14,26, etc., whose ending would bring to an end of time prophecy as a test for God's people (Revelation 10:6), for the little book is that portion of Daniel's prophecy that had been sealed, but was then opened after a certain time, able to be understood.
Here is a prophetic chart with all the dates and times, and events past, present and future (within reason) marked out. All may be historically and scripturally evidenced, as for instance:
*“...to determining when the reign of Tiberius Caesar started. The traditional approach is … that the reign of Tiberius started when he became co-regent in 11AD, placing the start of the ministry of John the Baptist around 26 AD. ...” - Wikipedia; "Baptism of Jesus"
The beginning of the 7th Year of Artaxerxes I Longimanus/Machrocheir's reign was in 457 BC fall:
"... Ezra thereby left Babylon in the first month of the seventh year (457 B.C.) of Artaxerxes' reign, at the head of a company of Jews that included priests and Levites. ..." - Wikipedia; Artaxerxes I of Persia
"... Artaxerxes I issues a decree to rebuild Jerusalem. ..." - Wikipedia, 457 BC
So, since there are 3 “decrees” and 1 set of “letters” in scripture given, the only dates which can apply to the Daniel Prophecy are these (following) alone, and only to one of them can the 483 years be added [69 weeks of the 70 weeks],
[1.] The decree of Cyrus recorded in Ezra 1:1-4. 536/538 BC
[2.] The decree of Darius I recorded in Ezra 6:1-12. 520 BC
[3.] The decree of Artaxerxes I (Longimanus) recorded in Ezra 7:12-26. 457 BC
[4.] The letters of Artaxerxes mentioned in Nehemiah chapters 1 and 2. 444/445 BC
If we add 483 years [69 weeks of the 70 weeks], and then add 3 1/2 years until Christ's death, and 3 1/2 years until end of 70 weeks] to these dates, notice their timeframes and the impossibility of 3 of them to be relevant by Scriptural standards [Ezekiel 4:6; Numbers 14:34, etc as already cited]:
[1.] 536/538 BC + 483 years = BC 53/51 [still BC] + 3 1/2 years = 49/48/46 BC [still BC] + 3 1/2 years = 45/44/43 BC [still BC, end of 70 weeks]
[2.] 520 BC + 483 years = BC 37 [still BC] + 3 1/2 years = 33/32 BC [still BC] + 3 1/2 years = 29/28 BC [still BC, end of 70 weeks]
[3.] 457 BC + 483 years = AD 27 [no year 0] + 3 1/2 years = AD 31 + 3 1/2 years = AD 34 [end of 70 weeks]
[4.] 444 BC + 483 years = AD 40 [no year 0] + 3 1/2 years = AD 43/44 + 3 1/2 years = AD 47/48 [end of 70 weeks]
So, of the 4 possibilities, the first two [1. and 2.] are completely out of the question, being entirely too early, as they are not even close to Christ Jesus anointing [or even His birth], and also do not reconcile with the whole of Daniel [especially chapter 11, and the 'tax']. The fourth [4.] is also out of the question, being entirely too late even for His death.
The only option that is even of sense to the prophetic scriptures of Daniel, and also the events as described in Esther, Ezra, and Nehemiah, etc. is obviously the third [3.] choice, which is one of ordered mathematics, rulerships of kings and heads of state, scripture and God's providence.
We know by so many texts and historical record that it was indeed the year AD 31 in which Christ Jesus [Messiah the Prince] died, fulfilling Prophecy to the exact specifications set forth so many millennia ago in the Word of God.
457 BC is the beginning of the Decree in Ezra 7 and thus the 2300 day/years also ended in 1844 [and we can also know this by other corresponding prophecies preceding it which were also fulfilled].
Daniel 9:24 Seventy weeks are determined upon thy people and upon thy holy city, to finish the transgression, and to make an end of sins, and to make reconciliation for iniquity, and to bring in everlasting righteousness, and to seal up the vision and prophecy, and to anoint the most Holy. (see Matthew 18:22; for the Jews were given 490 years, as a nation, but in Acts 7, their final time (as a nation) was forever up; Hebrews 2:3.)
Daniel 9:25 Know therefore and understand, that from the going forth of the commandment to restore and to build Jerusalem unto the Messiah the Prince shall be seven weeks, and threescore and two weeks: the street shall be built again, and the wall, even in troublous times.
Ezra 6:14 And the elders of the Jews builded, and they prospered through the prophesying of Haggai the prophet and Zechariah the son of Iddo. And they builded, and finished it, according to the commandment of the God of Israel, and according to the commandment of Cyrus, and Darius, and Artaxerxes king of Persia.