Chronological Connundrum

This site has a cute chronology for the "Palestine National Authority" (although they do have a Palestine state flag"):

Chronology

23 Aug 1516 Palestine part of the Ottoman Empire.
26 Sep 1918 British occupation (Palestine).
14 Jul 1922 Palestine League of Nations mandate under
Britain (see Israel).
14 May 1948 Former British mandate of Palestine independent
as Israel; West Bank under Jordan, Gaza under
Egyptian administration.
22 Sep 1948 All-Palestine Government formed; recognized
in Oct 1948 only by Egypt, Lebanon, Saudi
Arabia and Syria. Ceases to function by
Feb 1949, formally abolished 1952.
24 Apr 1950 Jordan annexes the West Bank and East Jerusalem
(occupied since May 1948).

a) what was the land/country/territory prior to 1516? nothing to do with "Palestine"?

b) September as "British occupation"? What about General Allenby entering Jerusalem on foot on 11 December 1917?

Or, exactly what were the borders of "Palestine"? Maybe parts of Syria and Lebanon were included? Here's a chronicle of the military campaign:

The great coastal cities of Haifa and Accra fell by 25 September [1918]. So did Megiddo...Two days later, Allenby’s forces entered Syria and the Battle of Nablus was over.

...Allenby ordered his powerful cavalry to seize Damascus...Mustafa Kemal himself could hardly save his life. Damascus fell on 1 October 1918 and soon Beirut (TR: Beyrut) was occupied by the British...On 16 October, the headquarters of the Fourth Army was encircled and destroyed in Homs. The 48th Division attempted to stop the British, but could not prevent the British army to enter Aleppo on 25 October. Syria was lost.

...With the remnants of the army, Mustafa Kemal established a defensive position at Iskenderun against the British...The Yıldırım Army Group was dissolved on 7 November 1918.

c) actually, the full ratification of the Mandate was a year later, in 1923. "In June 1922, the League of Nations approved the terms of the mandate, with the stipulation that they would not come into effect until a dispute between France and Italy over the Syria Mandate was settled. That issue was resolved in September 1923."

PASSIA has it so:

1922

June 3: The British government issues White Paper on Palestine excl. Transjordan from scope of Balfour Declaration.
June 30: US Congress endorses Balfour Declaration.
July 24: League of Nations Council approves Mandate for Palestine without consent of Palestinians.

1923

Sept. 29: British Mandate for Palestine comes officially into force.

And let's remember that Palestine and Transjordan remained a single administrative unit until 1946.