The show is called "first republic" in its original title. Meaning the Czech (and Slovak) lands between the two world wars... It is more accurate, than the often used english title "history of Czechoslovakia" as there is not much history indeed...
The time is just a setting in a "Romeo and Juliet" style romance... you do not learn much about the country, nor about the time.. In fact it does not really seem very realistic... It's more like if you put people from now in 100 years old costumes (which is very well done, though).. You will see a "regular" soap opera full of completely illogical scenes and plots.. The main character jumps from bed to bed, completely omitting the fact, that she have made 2 kids soon after she married a guy she didn't love.... and suddenly, one day she hates her ex, the second day she sleeps with him in a bed of her brother's flat without even closing the curtain, so people passing by on the street can see them... Even today, they would be much more cautious and 100 years back, it was culturally much less acceptable as presented in the show...
It seems that the episodes were developed based on the review from audience given to the previous episodes... Nevertheless, it is a nice show despite the discrepancies and too big focus on the secret romance... From history you however learn close to nothing... maybe about the money reform and creating of big Prague :D
UPDATE: After seeing the second season I consider to change my rating... 7 stars as for the first season is way too much.. due to the stupidity of the plot the second season deserves no more than 4 stars...
UPDATE 2: if the second season was 4 stars, the third may hardly get 2... The show evolved into some weird soap opera... it doesn't make any sense.. even in one single episode one character is the most hated at the beginning, but after 2 scenes biggest hero swinging back and for several time during a single episode... I understand that the authors wanted to keep audience thrilled, but it had completely opposite effect. And moreover the new characters are really uninteresting, some even annoying.. Actually I was usually just having the TV on, but didn't really pay full attention anymore... Next season may be interesting... with the raise of nazism... it is not sure, whether there will be 4th season, I will however not be interested in seeing it..