About ensured and well-established

[Mrxkms]

"This strategic location ensured that Palmyra prospered in a well-established kingdom from 2BC onwards"

I want to ask about ensured and well-established in this context
does ensure mean guarantee as it is in the dictionary ?
and what about well-established ? does it mean It is established well or strongly
would you please simplify the above mentioned clause to me ?

one last thing
I'd like you to provide me with some information about 2BC

[Cerberus™]

Yes, to ensure means to guarantee, to make certain that something will happen. It is used a bit loosely in this sentence.

Well-established is a somewhat vague word in this context. It is usually said of a shop or a law. I would take it as strong, well organised, and respectable.

I don't understand the "in": Palmyra was not in a kingdom, it was a kingdom itself at the time. It was more or less a city-state. "In the form of a kingdom" seems unlikely.

You could rephrase it as: "this strategic location was the reason why Palmyra prospered as a well-organised kingdom".

2 BC stands for the year 2 Before Christ.

[Milanya]

ensure - made certain
well-established - permanently founded; settled; firmly set
www.dictionary.com
The location fo Palmyra was very convenient. It was a vital caravan city for travellers crossing the Syrian desert.
Because of its location Palmyra became a prosperous and stable kingdom. The city was first mentioned in the archives of Mari in the 2nd millennium BC.

2nd millennium BC was about 4 thousand years ago.

Why did you make your print that big? It is hard to read.
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con·text - The part of a text or statement that surrounds a particular word or passage and determines its meaning.