How to automate left join of multiple data frames with single data frame one by one in R
If your data resides in clean form inside a database already:

write an sql statement that includes a series of UNION statements for your 206 country tables. You can use R or any other programming language to create this string.  

save this series of 206 UNIONs as a view (maybe as an indexed view / materialized view), or as  a new table, or as a stored-procedure that creates a temp-table on your database server

perform one SQL join on the DB server

fetch the data batch-wise