Found an article about a group of people named The Hittites who were also known as the adversaries of gods(one who oppose gods just like the One piece characters with .D in their name) they used to have a kingdom named Hittite Empire ,Hattusa( in my point of view The great kingdom) which was destroyed and new kingdom was formed about 100 years later. This 100 year period was known as dark age ( Void Century in one piece world) offcourse about which little is known until 10000 clay tablets with info about Hittites and their activity (i.e damn Poneyglyph) were found written in Akkadian script( poneglyph were written by Kozuki Clan in their language) which was decrypted by many scholars ( genius Ohara's scholars) but only one known( Nico Robin).
Also, we know in one piece world Nefertari family were among 20 countries to form World government but later on they moved to the low land.. Nefertiti; (from which Nefertari family name was made) An ancient egyptian queen husband Akhenaten created entirely a new capital in desert named Amarna (Alabasta) and later in Amarna letters were found showing the diplomatic relation with other countries and emerging of a powerful kingdom named Hittites Empire. Though other Egyptian king would likely to fight against the Hitties Akhenaten did nothing ( in one piece world also Nefertari family left Mariejois and they are called traitor).
I don't know whether somebody have already published what I am saying and also I don't know what I am saying is the fully the background part of One Piece story but while reading these articles each and every part reminded me of One piece. I will attach the link of articles hope some body will read it.