If the time period is in the future, you can either set up a TweetReach Tracker before the time period begins and it will capture all tweets in real time. Or you can run a snapshot report after your time period, which can include up to 1500 tweets from the past 4-5 days. To help decide what type of reporting you'll need, read this. 

If the time period is within the past few days, run a one-time snapshot report. A report will include up to 1500 tweets from the past 4-5 days. If you have more than 1500 tweets, you could run one report per day using date filters and get up to 1500 tweets per day. 

If the time period is more than a week ago, then we can't access those tweets.